It has been reported that a high proportion of abdominal fat is associated with increased plasma androgen concentrations in women. Although less evidence is available, abdominal obesity appears to be associated with low plasma testosterone (T) levels in men. We have therefore examined in 80 men (aged 36.3 +/- 3.2 years, mean +/- SD) the correlations between body fatness, adipose tissue (AT) distribution measured by computed tomography (CT), and circulating levels of the following steroids measured by radioimmunoassay after extraction from serum and chromatography: dehydroepiandrosterone (DHEA), androstenedione (delta 4-DIONE), androst-5-ene-3 beta,17 beta-diol (delta 5-DIOL), T, estrone, and estradiol. Sex hormone-binding globulin (SHBG) levels were also determined. T, adrenal C19 steroids, and SHBG levels were negatively correlated with total body fatness indices and abdominal fat deposition measured by CT (-.23 < or = -.55, .0001 < or = P < or = .05), whereas estrone showed positive correlations with these body fatness and AT distribution indices. Covariance analysis showed that after control for the concentration of the adrenal steroid precursor delta 5-DIOL, there was no residual association between T levels and adiposity variables. Furthermore, multivariate analyses showed that steroid and SHBG levels could explain from 20% (visceral AT area measured by CT) to 40% and 42% (body mass index [BMI], waist circumference, and waist to hip ratio [WHR]) of the variation in adiposity variables (.0001 < or = P < or = .05), with delta 5-DIOL being the best single correlate of body fatness and abdominal fat deposition in men.(ABSTRACT TRUNCATED AT 250 WORDS)