As part of the PRC-USA collaborative research project on the epidemiology of cardiovascular disease, baseline surveys were conducted in four random urban and rural samples in Guangzhou, Guangdong Province in southern China on 334 men and women aged 35-54 in the fall of 1983-84 with the aim of studying the correlation between dietary intakes and serum lipids. Methods standardized by the US Centers for Disease Control were used for measuring different parameters, and quality control was emphasized to assure comparability between workers and farmers. Three 24-hour recalls were collected from each participant in each survey. Mean values of daily intakes of nutrients per capita for the four groups were as follows: 59-69% kcal carbohydrate; 10-12% kcal protein; 22-26% kcal fat. Dietary total fat, saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA) and cholesterol were higher in the urban than the rural areas. Mean levels of serum total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were 4.6 mmol/l, 1.1 mmol/l, 1.3 mmol/l and 2.8 mmol/l respectively. The TC, TG and LDL-C and HDL-C were significantly higher in the urban than the rural areas. Analyses of correlation showed that the Keys 'dietary lipid score' was positively associated with TC, LDL-C and HDL-C; specifically, dietary cholesterol was positively associated with serum TC. Saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were positively correlated with HDL-C. It seems that the traditional dietary pattern of Guangzhou favours serum lipids being at an optimal level.