,A retrospective case-control study of totally 573 (3x191) subjects wasinvestigated.They come from residents living in the urban area of Shanghai for more than ten years at an age interval from 30-70. Every case waspaired by two controls. They were all inquired by a same interviewer with a carefully prepared questionaire list which involved past dietary habits and other factors thought to be related to breast cancer. From these data our tentative impressions are as follows. Rich fat (80g) and protein (80g) diet is closely associated with breast cancer. The relationship is much more significant among the patients over 50 years old than those under fifties. The consumption of carbohydrate and crude fiber showed, in this study, no association with the carcinogenesis of breast cancer. The risk of polyunsaturated fatty acid is higher than saturated fatty acid in association with breast cancer. The more the animal protein intake (30g), the higher risk of breast cancer occurs, and soybean protein tends to decrease the risk of breast cancer. There are multiple etiological factors for bre- ast cancer, however nutrition and diet would be considered as one of the important factors. With regard to the dietary component, animal foods such as eggs and pork may increase the risk of breast cancer. But as a whole, the dietary component of the patients studied here is rather proper. Obesity as shown by the increased skinfold thickness is one of risk factors for breast cancer. Finally breast cancer patients have a normal level of blood lipids, but their HDL-cholesterol is lower than that of control groups.