Introduction: Orofacial clefts are the most common congenital malformations that affect craniofacial structures. Disjunction of skin, muscles, bones and cartilages represents an aesthetic and functional problem. Clefts can be a result of a large number of syndromes or non-syndromic, i.e. isolated, but in both cases, they are divided into cleft lip, cleft lip and palate or isolated cleft palate. Children born with this type of malformation have difficulties with talking, hearing, dental irregularities and characteristic changes in the appearance of the nose and lip, which affect all domains of health. Studies show that orofacial clefts have a major influence on psychological development of the patient and their families. The treatment of children with clefts is comprised of a large number of specialists whose activities are intertwined through the period of growing up, and includes a maxillofacial surgeon who coordinates other team members, a neonatologist, an anaesthesiologist, a paediatrician, an orthodontist, an oral surgeon, an otorhinolaryngologist-audiologist, a logopedist, a psychologist, a psychiatrist, and a paediatric dentist. It is necessary to understand the embryonic development of the nose, lip and palate between the 4th and 10th gestational week in order to grasp the formation of the orofacial cleft. The development of a normal palate is explained by the fusion of facial extensions, i.e. the penetration of mesoderm into the primary and secondary palate. According to His’s theory of facial extensions (1892), orofacial clefts are a consequence of inhibition of growth and binding of embryonic facial extensions. The incidence of orofacial clefts, according to the latest data, is about 1 out of 700 children born in the world. In Croatia, according to Magdalenić-Meštrović's research from 2005, the incidence is somewhat higher, and that is 1 in 581 born children. Cleft lip with or without cleft palate is more common in the male sex, and isolated cleft palate in the female sex, regardless of ethnicity. If the ratio of the sexes only in the white race is taken into consideration, then cleft lip with or without cleft palate is more common in the male sex in the ratio of 2:1. Epidemiological and experimental data suggest that harmful environmental influences may have a significant effect on the formation of cleft lip and/or palate in the form of exposure to the mother's tobacco smoke, alcohol, nutritional deficiency, viral infections, medical preparations and other teratogens at work and at home in the early months of pregnancy. Procedures and protocols for treating children with a cleft lip and palate can be extremely different within and among developed countries. Cleft treatments aim at correcting the broken anatomical relationship and establishing a normal function of the broken tissue and surrounding structures. Irregularities regarding the facial appearance, speech, maxillofacial and dento-occlusal development, hearing, and psychosocial status are attempted to be corrected, i.e. alleviated by various invasive and non-invasive therapeutic procedures. Most maxillofacial surgeons operate the cleft lip after the third month of age. This observes the anaesthetic "rule of ten” when a child is at least 10 weeks of age, has haemoglobin above 10 dg/L and weight above 5000 g (10 pounds). The surgical procedure of closing the soft palate in complete clefts is most commonly performed between the 3rd and 6th month of age, at the same time as the lip operation is performed. The malformation on the hard palate is corrected in the second operation around the child’s second year. In cases of isolated cleft palates, the closure is also performed in two operations; first the soft palate between the 3rd and 6th month, and then the hard at two years of age. In 1948, the World Health Organization defined health as a state of complete physical, mental and social well-being, not just the absence of disease and inactivity. American psychologist John C. Flanagan is considered to be the founder of the concept of quality of life in health care. HRQOL – health related quality of life describes subjective satisfaction with one’s health status. It is an instrument which examines the impact of illnesses and treatment modalities on health, integrating an objective assessment of the health status and its subjective experience (satisfaction with physical, mental and social functioning). The concept of oral health-related quality of life (OHRQOL) has only been developing over the past few decades, since it started to draw close attention. Oral health is considered an important part of a patient's general health. In Croatia, no studies have been conducted on this issue. Therefore, research is needed to investigate the impact of orofacial clefts on the quality of life of operated children and their parents. In this way, the results of the treatment and the quality of work of the health team involved in this process would also be seen. Examinees and research methods: For the purpose of this study, original questionnaires were put together to research the effect of orofacial clefts on the quality of life in operated children and their parents. In cooperation with a maxillofacial surgeon, an orthodontist, a psychologist and a logopedist who have longterm experience in treating clefts, questionnaires for children with clefts, their parents/guardians, and a form for taking the clinical status, which the examiner fills in during the interview and examination of the patient, were made. The questions were carefully designed and chosen to be as adjusted as possible to research groups, and to achieve the main goals of the research. The study was conducted at the Clinical Institute for Oral Surgery, the Clinic for Face, Jaw, and Mouth Surgery, Clinical Hospital Dubrava, Zagreb, and it includes 73 examinees, or 11 – 18 year-old children, who have one form of operative orofacial cleft and the equal number of their parents/guardians. The female sex was more represented with 56.2% of respondents, or 57.1% in the control group. The respondents were divided into two age categories (groups) to identify possible differences in early and late puberty. From the collected questionnaires, it was determined that representation in the older age group was similar for both groups of respondents (57.5% vs. 62.9%). The questionnaires consist of a general part, which the respondents filled in with their sex and age, and questions that examined quality of life. The questionnaire for children contains 46 questions/claims, and the one for parents 28 questions/claims. The questionnaires are made of simple statements which are evaluated with a 5-degree Likert scale (from 1 – fully disagree to 5 – fully agree) so they do not require specific additional clarifications, and are easy to fill in. After the questionnaires were completed, the examiner checked the patients/children and filled in the clinical status template located on a separate questionnaire sheet. The described study focuses on the fact of obtaining the patients and their parents’views on the long-term treatment process and the impact of the treatment on the quality of life. Results and discussion: Most children (46.6%) had unilateral cleft lip and palate. Only 6.8% of children had cleft presence in family, and less than 10% of children had 7 or more surgeries. Most children were happy with the appearance of the nose and lip. Almost a third of the respondents have a fistula on the palate, whereas 45.2% of the respondents have an occlusion Class 3 by Angle. Original questionnaires specific for assessing aesthetic and functional outcomes of the treatment, i.e. the quality of life in the operated child and his parents, were designed in this research. The illustrated results show the children and parent’s views, as well as aesthetic and functional factors that have the highest impact on the quality of life. Analysing the results of this research, we come to the conclusion that the studied group has worse results (higher score in response evaluation) compared to its control group, resulting in poorer quality of life as a consequence of the orofacial cleft. The results of this study did not reveal statistically significant differences in the responses of children with clefts regarding the sex. The proportion of male and female respondents was 32- 43.8%: 41-56.2%. Despite the fact that the female respondents were more dissatisfied with the aesthetic component of the cleft (external appearance, nose, lip and teeth), and the male respondents with the functional component (speaking, chewing), there were no major differences in the responses on the Likert scale. We divided the respondents into two age groups: younger adolescents 11 – 14 years (31 respondents – 42.5%) and older adolescents 15 – 18 years (42 respondents – 57.5%). The results show that there are differences in the responses between these two groups,but they are not statistically significant. The exploratory factor analysis of all 46 claims in the questionnaire intended for studying children with clefts gave three factors that evaluate the effect of the orofacial cleft on the quality of life. Three factors represent three categories: 1.Relationship with parents, success, society, 2.Appearance and 3.Function, which are integral part of a conceptual life quality scheme that consists of three main domains: physical, psychological and social health. Factor 1 Relationship with parents, success, society is a component of social health, factor 2 Appearance is a component of psychological health, and factor 3 Function is a component of physical health. The observed results show that the differences were significant for all three domains, with the emphasis on the fact that the biggest difference was in the domain of psychological health, i.e. appearance, which is the expected result since the answers given to individual questions referred to such a result. The data from the clinical form were compared with individual domains, and thus an "external" response validation was made, i.e. a comparison of subjective and objective experience of the cleft. A positive correlation was determined between a worse nose and lip appearance and the appearance domain, as well as a higher class by Angle (maxillary retrognathia / mandibular progenia) and the function domain. The questionnaire intended for parents shows that they have a satisfying quality of life. Factorial analysis of the questionnaire for parents of children with the orofacial cleft has formed two domains: Social health of parents and Social health of the child. Despite the fact that the results of this research have confirmed that the parents’quality of life is not disturbed, and taking into consideration the children’s quality of life as perceived by the parents, it has been confirmed that their opinion is closely related to the children’s opinion. There are positive correlation coefficients if we analyse similar questions in both questionnaires and when the parents’perception on the child's social health is analysed with the children’s perception in all three domains. Conclusion: The scientific contribution of this research consists of created and applicable original questionnaires specific for assessing the influence of orofacial clefts on the quality of life in operated children and their parents. Aesthetic factors which affect the quality of life of children born with a cleft lip and palate the most are the appearance of the nose and lip, and the functional factors with the most influence are dental malocclusion and speech difficulties. Based on the presented results, it can be concluded that the congenital malformation, the orofacial cleft, with its clinical manifestation and the scope of affected anatomic structures, decreases the quality of life in treated children regarding the postoperative function and aesthetic outcome. On the other hand, we have come to the conclusion that the quality of life in parents of treated children is not diminished, although the parents’ opinion coincides with the children’s opinion on their quality of life.