The purpose of the study was to investigate the associations of abdominal obesity and overall obesity with the risk of acute coronary events. Body mass index indicating overall obesity and waist-to-hip ratio and waist circumference indicating abdominal obesity were measured for 1346 Finnish men aged 42-60 years who had neither cardiovascular disease nor cancer at baseline. There were 123 acute coronary events during an average follow-up of 10.6 years. In Cox regression analyses adjusted for confounding factors, waist-to-hip ratio (P=0.009), waist circumference (P=0.010) and body mass index (P=0.013) as continuous variables were associated directly with the risk of coronary events. These associations were in part explained by blood pressure, diabetes, fasting serum insulin, serum lipids, plasma fibrinogen, and serum uric acid. Waist-to-hip ratio of > or =0.91 was associated with a nearly threefold risk of coronary events. Waist-to-hip ratio provided additional information beyond body mass index in predicting coronary heart disease, whereas body mass index did not add to the predictive value of waist-to-hip ratio. Abdominal obesity combined with smoking and poor cardiorespiratory fitness increased the risk of coronary events 5.5 and 5.1 times, respectively. Abdominal obesity is an independent risk factor for coronary heart disease in middle-aged men and even more important than overall obesity. Since the effect of abdominal obesity was strongest in smoking and unfit men, the strategy for lifestyle modification to prevent coronary heart disease should address these issues jointly. Copyright 2001 The European Society of Cardiology.