This thesis aims to describe cases of suspected off-label use of drugs spontaneously reported to the Croatian Agency for Medicinal Products and Medical Devices in the pediatric population in the period until the end of 2021 (December 31st). By the end of the same year, there have been identified cases of reporting the suspicion of off-label use of the drug by patients younger than 18 years old. Primary analyses were made for the reports of suspected adverse reactions belonging to High-Level Term: Off-label uses according to MedDRA. Reports were investigated according to the age and sex of the patient, the reporter qualification, the active ingredients, the ATK classification of drugs, the PT classification of MedDRA, and the severity of side effects. A total of 36 reports of suspected off-label use of drugs by patients younger than 18 years old were received. Most applications were received for children between 2 and 11 years old. The lowest number of applications was received for newborns, from 0 to 27 days of age. According to the ATK classification of drugs, drugs with effects on the nervous system, drugs with effects on systemic infections, drugs with effects on the respiratory system, and drugs with effects on the senses were the ones that were the most often included. The most commonly suspected active ingredients were paliperidone, diclofenac, pantoprazole, and micafungin. Out of a total of 36 received reports, there were 3 cases with no side effects developed, 21 cases with side effects we consider to be frivolous, and 12 cases with severe side effects developed (including 3 cases in which death occurred). This thesis identified the need for improvements in the pharmacovigilance system and the need to educate healthcare professionals and patients about reporting the off-label drug use and the side effects that arise from using them.