The association between consumption of fat and specific types of fat and the risk of breast cancer has been examined in previous studies, but the results remain unclear. Moreover, few studies were conducted in China, where dietary habits are different from those of the Western countries. We conducted a hospital-based case-control study from June 2007 to August 2008 among Chinese women residing in Guangdong to investigate the associations of dietary fat and specific types of fat with the risk of breast cancer. Four hundred and thirty-eight consecutively recruited cases with primary breast cancer were frequency matched to 438 controls by age (5-year interval) and residence (rural/urban). Detailed dietary intake information was assessed by face-to-face interviews with a validated Food Frequency Questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were obtained from multiple unconditional logistic regression models controlling for nondietary and dietary potential confounders. Total fat intake was not associated with the risk of breast cancer after adjustment for various confounding variables (OR = 0.82, 95% CI = 0.50-1.32, Ptrend = 0.739). Intakes of saturated fat, monounsaturated fat, n-3 polyunsaturated fat, and n-6 polyunsaturated fat were also not significantly associated with breast cancer risk. However, consumption of polyunsaturated fat was observed to be associated with a significantly lower risk of breast cancer. Compared with the lowest quartile, the adjusted OR in the highest quartile was 0.50 (95% CI = 0.27-0.93, Ptrend = 0.034). This study suggested that intakes of total fat, saturated and monounsaturated fat, n-3 and n-6 polyunsaturated fat were not associated with risk of breast cancer, but that polyunsaturated fat decreased the risk.