Objective: To investigate the distribution of waist circumference (WC) and waist-to-hip ratio (WHR), their relationships with a number of established risk factors and their relevance to cardiovascular morbidity in a random sample of Turkish general adult population. Design: Cross-sectional population-based study. Subjects: The subjects comprised 958 men and 1014 women, aged 25-74 years. Measurement: Waist circumference was measured midway between the lower rib and iliac crest while that of the hip at the level of trochanters. Mean of two blood pressure measurements was used for analysis. Plasma total cholesterol (Cho) and triglyceride (Trg) concentrations were measured by the enzymatic dry method with a Reflotron apparatus. Results: Overall mean WC measured 93+/-12 cm in men, and 88.6+/-13 cm in women. Mean WHR was 0.919+/-0.077 and 0.823+/-0.074, respectively, and a rise by about 0.001 was associated with each year of age. In multiple regression analysis a model was utilized that included age, body mass index (BMI), systolic and diastolic blood pressure (BP), plasma total Cho and Trg and category of smoking. This revealed age, BMI, and Trg as independent determinants of WHR in both genders, and diastolic BP in women alone. Age, BMI, and diastolic BP proved to be independently associated with WC in both genders, while Cho did so in men alone, Trg and systolic BP in women alone. Partial correlation coefficients on univariate analysis between all four variables of blood pressure and plasma lipids and either WC or WHR, controlled for age, were highly significant though moderately weak in both genders. These were stronger in men than in women, and stronger with respect to WC than to WHR. Cigarette smoking men and women had significantly lower WC or WHR than nonsmokers and ex-smokers, though these associations did not prove to be independent. When the relevance of WC and WHR to CHD risk was tested in this cohort (for the age bracket 45-74 years) comprising 138 cases with a clinical diagnosis of CHD, only WHR in women proved to be significantly associated. Odds ratio for a value of >0.845 was 1.6. Conclusion: WC and WHR are strongly associated with BMI and age as well as with parameters reflecting insulin resistance such as diastolic blood pressure and plasma triglycerides. WHR was significantly associated with coronary heart disease in Turkish women. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.