Ovarian and fallopian tube cancer, i.e., adnexal tumours, and primary peritoneal cancer is the sixth most common female cancer and the deadliest gynecologic tumor in Croatia. Hystologically, these tumors are most commonly of epithelial origin, a serous subtype. Less common are various non-epithelial ovarian malignancies, as well as ovarian metastases. A special group consists of epithelial carcinomas of low malignant potential characterized by non-invasiveness, clinically indolent course, and good prognosis. Clinically, these cancers are generally asymptomatic in early stages, and therefore usually diagnosed in later, advanced stages. The diagnosis is confirmed by pathological examination, or exceptionally by cell block cytology finding after the completion of diagnostic procedures. Multidisciplinary team makes treatment and follow-up decisions, taking into account patients’ (age, general condition, and comorbidities) and tumor characteristics (stage of disease, histological type and grade, homologous recombination status or BRCA gene 1 and 2 status, as well as the response and toxicity to previous treatment in case of relapse). The treatment of primary ovarian, fallopian tube, and peritoneal cancer is based on surgical procedures, systemic administration of chemotherapy, immunotherapy, targeted therapy and hormone therapy, as well as symptomatic-supportive measures throughout the whole treatment. Treatment approach differs in less frequent non-epithelial histological types of these tumors because they are commonly diagnosed in early stages of the disease, have a more indolent course, different disease biology and sensitivity to systemic treatment. The following text presents the updated and supplemented clinical guidelines in order to standardize procedures and criteria for diagnosis, management, treatment and monitoring of patients with ovarian, fallopian tube, and primary peritoneal cancer in Croatia. The first edition of the guidelines for diagnosis, treatment and monitoring of patients with ovarian cancer was published in 2013.