In the old and newly recruited cohorts of the Turkish Adult Risk Factor Study consisting of 2350 men and women (mean age 52±12 years), body mass index (BMI), waist circumference and waist-to-hip ratio (WHR) were assessed cross-sectionally and prospectively. Coronary heart disease (CHD) was diagnosed based on clinical findings and Minnesota coding of resting electrocardiograms. At standardized age, mean waist circumference and BMI in men were 90.7 cm and 27.3 kg/m2, respectively, and in women 90.8 ile 29.1 kg/m2, respectively. It is estimated that 10.5 million adults (22.6% of men and 61% of women) in Turkey may be designated to have abdominal obesity. Following difference in magnitude or ratio of variables existed across the highest and lowest quintiles of waist circumference: 22 mg/dl in apolipoprotein (apo) B, 3.5-fold to 2-fold in C-reactive protein (CRP), 2 to 2.4-fold in fasting serum insulin concentrations. Furthermore, diabetes was more frequent by 2.2-fold in men and by 4.8-fold in women across these quintiles. In a logistic regression analysis over a 4-year follow-up, waist circumference significantly predicted nonfatal and/or fatal CHD risk in men, and among men and women combined, independent of 9 other salient risk factors, imparting 35% excess risk for each increment of 12 cm (= I SD) of waist circumference. In the presence of the latter, BMI failed to contribute to CHD prediction. It was concluded that abdominal obesity in Turkish adults not only substantially elevated the concentrations of important cardiovascular risk factors such as serum apo B, insulin, CRP, and the prevalence of type II diabetes, but also contributed independently to cardiovascular morbidity and mortality, particularly among men. The "curve" between CHD risk and the stated atherogenic risk factors suggested that Turkish men with a waist circumference of 96 cm should be considered at the "action level". These findings should guide fitture public heart health policies.