Introduction: Granulosa cell tumors of the ovary (GCT) are derived from the sex cords and the ovarian stroma. Their natural history, however, is indolent with a very favorable long-term prognosis. Their extreme rarity represents a limitation in our understanding of their natural history, management, and prognosis. Material and methods: Retrospective analysis of patient documentation treated for GCT between 1988-2008 at the Maria Skłodowska-Curie Memorial Cancer Centre, Warsaw, was performed. Clinical and pathological features of the study group, as well as methods and results of the treatment were analyzed. Results: Medical documentation of 148 patients was analyzed. The majority of patients was classified as FIGO stage I (87,5%). Surgery was performed as primary treatment in all cases. Forty eight patients (32,6%) were held for observation stays, whereas 57,1% were qualified to receive adjuvant treatment: chemo- or radiotherapy. Mean progression free survival was 133,5 months (11,1 years) and was significantly longer in patients treated with the chemotherapy regimen when compared to radiotherapy (148 vs 91 months respectively; p=0,028). Overall survival was 173,7 months and was significantly longer in patients treated with adjuvant chemotherapy vs. RTH (165 vs. 121 months; p=0,068). Recurrence of the disease was associated with poorer prognosis. Conclusions: GCTs are potentially curable neoplasms of the ovary with low treatment failure rates. Quick diagnosis and appropriate treatment in centers experienced in ovarian cancer surgery are the necessary conditions to obtain good results. The stage of the disease remains the most important prognostic factor. Chemotherapy with the use of bleomycine etoposide and cisplatin should be considered in patients who require adjuvant treatment.