Turkish men and women have about 20% lower mean levels of HDL-C and apoA-I than German individuals. To obtain some information on the metabolic basis of this difference, we compared anthropometric data as well as serum levels of leptin, insulin, testosterone (T), estradiol (E2), and sex hormone binding globuline (SHBG) in 289 German and 120 Turkish men as well as in 108 German and 182 Turkish women aged 20-60. Individuals who smoke, take hormones, have overt diabetes mellitus, BMI > 30 kg/m2, triglycerides > 400 mg/dl, or LDL-cholesterol > 200 mg/dl were excluded. In both sexes, Turks had significantly lower levels of HDL-C, apoA-I, Lp(a), and SHBG than Germans. Moreover, German men had a larger waist circumference, lower levels of E2 and a lower ratio of T/SHBG. German women also had a lower BMI, smaller waist circumference, lower insulin levels and higher T levels. Mean values of age, waist-hip-ratio (WHR), leptin, triglycerides, LDL-C, and apoB did not differ significantly among Germans and Turks. Upon univariate analysis HDL-C had inverse correlations with BMI, waist circumference, WHR, leptin, and insulin as well as positive correlations with SHBG in both sexes. Upon multivariate analysis, most of the different levels of HDL-C and apoA-I between Germans and Turks were explained by ethnicity, independently of obesity markers, insulin, and sex hormones.