Background: Evidence that links dietary factors to ovarian cancer is conflicting, but several epidemiologic studies suggested that consumption of dietary fat and meat may increase risk of ovarian cancer. Objective: We studied associations of intakes of total fat and sources and subtypes of fat, fresh meat, processed meat, and fish with ovarian cancer risk within the Netherlands Cohort Study (NLCS). Design: The NLCS includes 62,573 postmenopausal women, aged 55-69 y at baseline, who completed a baseline questionnaire on dietary habits and other risk factors for cancer in 1986. After 16.3 y of follow-up, 340 ovarian cancer cases and 2161 subcohort members were available for a case-cohort analysis. Multivariable rate ratios (RRs) were adjusted for age at baseline, total energy intake, oral contraceptive use, and parity. Results: There were no clear associations between intakes of total fat, saturated fat, mono-and polyunsaturated fats, animal fat, plant-based fat, dairy fat, other fat sources, fresh meat, processed meat, and fish and ovarian cancer risk. There was a positive association between consumption of trans unsaturated fatty acids and ovarian cancer risk. The multivariable RR for women in the highest compared with the lowest quintiles of intake was 1.51 (95% CI: 1.04, 2.20; P for trend = 0.01). Although no significant interactions by oral contraceptive use or parity were shown, effect sizes were generally more pronounced and significant in women who never used oral contraceptives and in parous women. Conclusion: This prospective study suggests that trans unsaturated fatty acids, but no other types of fat or meat, are associated with increased ovarian cancer risk. Am J Clin Nutr 2011;93:118-26.