A case-control study was conducted in Moscow to assess the effect of diet on risk of breast cancer, and also to study the established reproductive risk factors. A notable finding of the study, which covered 139 case-control pairs matched by age and neighbourhood, is that dietary factors are more important for post-menopausal than for pre-menopausal breast cancer. The decreased risk of post-menopausal breast cancer was associated with high intakes of cellulose (OR 0.04; 95% CI 0.01-0.31), mono-and disaccharides (OR 0.02; 95% CI 0.002-O.Z7), vitamin C (OR 0.20; 95% CI 0.06-0.70), beta-carotene (OR 0.09; 95% CI 0.OM.49), and also polyunsaturated fatty acids (OR 0.14; 95% CI 0.03-0.69). High intakes of total fat resulted in a statistically non-significant decrease in the odds ratio (OR 0.52; 95% CI 0.04-6.99), while saturated fats slightly increased the risk of breast cancer (OR 1.67; 95% CI 0.24-11.78). Protein intake was also associated with increased risk of breast cancer (OR 4.62; 95% CI 0.69-30.70). Alcohol use significantly increased the risk of breast cancer in postmenopausal women (OR 3.39; 95% CI 1.37-8.38). In general, the results of our study indicate that high risk of breast cancer is associated with high intakes of nutrients derived from animal products, and low risk with high intake of those from vegetables and fruits.