1. The aim of the present study was to investigate the trend of the prevalence of obesity in China and its association with hypertension and hypercholesterolemia. 2. A multicentre cross-sectional study was conducted in Chinese men and women aged 48-56 years between 1985 and 2000. In the report, three study periods were classified as survey 1 (1985), survey 2 (1988-1989) and survey 3 (1997-2000) in order to describe the long-term trend. 3. The results show that: (i) mean body mass index (BMI), prevalence of obesity (BMI > or = 28 kg/m2) and overweight (BMI > or = 25 and < 28 kg/m2) increased significantly from 1985 to 2000 in both sexes (P < 0.001); (ii) similar to the trend for BMI, the prevalence of hypertension and hypercholesterolaemia (total cholesterol (TC) > or = 220 mg/dL) also increased significantly from 1985 to 2000 (P < 0.001); (iii) partial correlation and multiple linear regression analyses indicated that increased BMI was significantly positively correlated with blood pressure and TC and negatively correlated with serum high-density lipoprotein-cholesterol (P < 0.01 or P < 0.001); and (iv) multiple logistics regression analysis models indicated that obese subjects had a 3.9-fold higher risk of being hypertensive (relative risk (RR) 4.9; 95% confidence interval (CI) 3.4-7.3) compared with those subjects who had a BMI less than 25 kg/m2. The corresponding RR (95% CI) of obesity for hypercholesterolaemia was 2.63 (1.57-4.40). 4. In conclusion, the results highlight the epidemic of obesity, an emerging risk in China. Great efforts must be made to alter this unwelcome trend.