Background: Dietary fat has been inconsistently associated with the risk of breast cancer. The purpose of this study was to examine the relationship between meat and animal and plant fat intake and breast cancer risk in subgroups by total lifetime physical activity, using data from a case-control study conducted in the Region of Western Pomerania, Poland. Materials and Methods: The study included 858 women with histological confirmed breast cancer and 1,085 controls, free of any cancer diagnosis. The study was based on a self-administered questionnaire including questions about socio-demographic characteristics, current weight and height, reproductive factors, family history of breast cancer and lifestyle habits. Unconditional logistic regression was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Results: High animal fat intake significantly increased OR from 1.7 times (OR=1.66, 95%CI=1.07-3.59) to 2.9 times (OR=2.9, 95%CI=1.37-6.14) independent of physical activity level, comparing the third versus the lowest quartile. Women with a high intake of red meat or processed meat and low physical activity showed increased risk of breast cancer: OR=2.70, 95%CI=1.21-6.03 and 1.78, 95%CI=1.04-3.59, respectively. The plant fat dietary pattern was negatively associated with breast cancer in sedentary women (OR=0.57, 95%CI=0.32-0.99). Conclusions: These results indicated that a diet characterized by a high consumption of animal fat is associated with a higher breast cancer risk in sedentary women, while consumption of plant fat products may reduce risk in the same group.