Cystadenofibromas of the ovary are rather frequent benign tumours of the ovary. They take one fourth of all benign neoplasms of the ovary and 50-70% of all serous ovarian tumours. The pick incidence is in the fifth decade. The tumour is bilateral in 12-20% of cases, more frequently in elder women. The tumor appears in cystic, papillary, adenofibromatous and mixed forms. Cystic tumours are usually unilocular but may be multilocular. The size of the mass varies up to 30 cm, average size is 10 cm. We report on a 62 year old woman in whom a gigantic cystadenofibromas of the ovary, 29 kg of weight, 55 x 35 x 35 cm. in diameter, was removed. The recovery was uneventful and the patient stayed symptom-free. To our best knowledge this was the largest tumour of this kind ever reported.