Objective: Incidence of ovarian cancer varies greatly from one population to another, depending on the prevalent risk factors mostly influenced by menstrual-reproductive events and life style habits. It is hardly possible to present proper and updated data concerning Turkey due to the insufficiency of the statistical records. The aim of this study was to investigate the association between risk factors and ovarian cancer in Turkish women. Material and Methods: In a hospital-based case-control study in a university hospital in Istanbul, 217 patients with histologically confirmed ovarian cancer were compared with 1050 controls, who were admitted to the different departments of the same hospital. Data were collected using a structured questionnaire including questions about characteristics (age, education, marital status, body mass index, chronic diseases, smoking and alcohol), menstrual and reproductive history, and family history of cancer in all participants. Odds ratios (OR) and 95% confidence intervals (Cl) were obtained from multivariate logistic regression analysis, fitted by the method of maximum likelihood. Results: Risk factors for ovarian cancer were found to be the age (p=0.002), body mass index (BMI) (OR=1.96, 955/0 CI: 1.41-2.72) and history of diabetes or hypertension (OR=2.13, 95% Cl: 1.40-3.23), (OR=2.85, 95% Cl: 1.64-4.98). However, when compared with controls, it was found that the OR of non-smokers and the patients with a negative family ovarian cancer history; were 0.29 and 0.33. Conclusion: This study indicates that age, BMI and history of diabetes or hypertension and lower parity were strong risk factors for ovarian cancer.