OBJECTIVE The relationships between visceral fat distribution, steroid hormones and peripheral insulin sensitivity were studied. METHODS All subjects were hospitalized in the Institute of Internal Medicine of the University of Verona, Italy. METHODS Nineteen fertile obese women were studied with ages ranging from 18 to 53 years and body mass indexes ranging from 27.3 to 48.4. METHODS Body fat distribution was evaluated by waist-to-hip circumference ratio and by computed tomography. The insulin tolerance test was used to evaluate peripheral insulin sensitivity. Glucose, insulin and C-peptide were measured in fasting conditions and during glucose load; total and free plasma testosterone and urinary cortisol excretion were also determined. RESULTS Significant correlations emerged between visceral adipose tissue and fasting glucose, insulin, and C-peptide, but not between visceral adipose tissue and total testosterone, free testosterone or urinary cortisol excretion. A negative correlation emerged between visceral adipose tissue and insulin sensitivity (r = -0.70; P < 0.01). No significant correlations were found between insulin sensitivity and age, body weight, body mass index, total adipose tissue, subcutaneous adipose tissue or waist-to-hip ratio. Total testosterone correlated with body weight, subcutaneous adipose tissue and total adipose tissue. Free testosterone and urinary cortisol excretion correlated positively with body weight, and negatively with age. No correlation was found between insulin sensitivity and total testosterone, free testosterone or urinary cortisol excretion. The correlation between visceral adipose tissue and insulin sensitivity remained significant even after adjusting for both age and the body mass index. CONCLUSIONS Our study shows that visceral fat is more closely associated with aberrations of insulin sensitivity than with obesity itself. Total testosterone, free testosterone and urinary cortisol excretion in our subjects do not seem to be associated with such aberrations.