Objective: The influence of vitamin supplements on risk for breast cancer is unclear. Also the interactive effects of vitamins from dietary and supplemental sources are unknown. This study investigated the association between self-reported vitamin supplement use (A, B, C, E and multivitamin) and breast cancer among urban Chinese women. It also examined the combined effect of vitamin supplements in relation to particular dietary vitamin intakes on breast cancer risk.Methods: Study subjects were identified from The Shanghai Breast Cancer Study (SBCS) and was a population-based case-control study conducted in Shanghai in 1996-1998 (Phase I) and 2002-2004. Participants were aged 25 to 64 and 20 to 70 years for phase I and for phase II, respectively. The analyses included 3,454 incident breast cancer cases and 3,474 controls. Unconditional logistic regression models were used to determine adjusted odds ratios (ORs) for breast cancer risk associated with vitamin supplement use.Results: Overall, the breast cancer risk was not related to intakes of any vitamin supplement. However, an approximately 20% reduction in breast cancer risk was observed with use of vitamin E supplement among women with low-dietary vitamin E intake (OR=0.8; 95% confidence interval (CI), 0.6-0.9) with a significant does-response inverse association (P trend =0.01 for duration). Modest risk reduction was observed among vitamin B supplement users with low dietary intake of the same vitamin (OR=0.9; 95% CI, 0.6-1.0). However, vitamin B supplement was adversely associated with breast cancer risk among those with high dietary vitamin B intake with a significant dose-response effect (P trend =0.04 for duration).Conclusions: This study suggests that vitamins E and B supplement may confer a prevention of breast cancer among women who have low dietary intake of those vitamins.