The association of both leisure-time physical activity and obesity with lipoprotein-lipids and composite atherogenic markers were examined within a cross-sectional study of middle-aged men of higher socioeconomic status. Analyses were performed on a subsample (n=629) of non-smoking, non-diabetic men (46.7+/-7.8 years) who completed a preventive medical assessment between 1992 and 1996. Mean adjusted (age, body mass index (BMI), sum of skinfolds, fasting glucose, and logarithmic alcohol consumption) levels of high-density lipoprotein-cholesterol (HDL-C) were significantly higher, and logarithmic triglycerides significantly lower, with higher physical activity index (PAI) categories (both P<0.0001). Significantly lower adjusted mean ratios of both total cholesterol to HDL-C (TC:HDL-C), and logarithmic triglycerides to HDL-C (TG:HDL-C) with higher PAI were evident following adjustment for the above covariates (P=0.005 and P<0.0001), Age-adjusted non-HDL-C (total cholesterol minus HDL-C) decreased significantly with higher PAI categories, but was not significantly lower following covariate adjustment (P=0.150). On stepwise multiple regression, logarithmic physical activity score and BMI explained 9.5-14% of the variance in the TC:HDL-C and TG:HDL-C ratios in models including age, body mass, sum of skinfolds, fasting glucose and logarithmic alcohol consumption. Age, sum of skinfolds and logarithmic alcohol consumption were significant predictors of non-HDLC (r(2)=8.0%). These findings emphasise the importance of both physical activity and obesity in predicting lipoprotein-lipid risk markers.