A case control study was performed to determine whether the hypotestosteronaemia described in men with coronary artery disease could be the result of primary testicular dysfunction. Testicular function was assessed by comparing the response of 10 young Indian men with myocardial infarction to human chorionic gonadotrophin (HCG) injection to that of 10 healthy age and weight matched controls. The basal testosterone levels in the patients were significantly lower (12.71 +/- 1.36 nmol/l vs 16.51 +/- 0.79 nmol/l; P = 0.01) and the basal oestradiol levels significantly higher than the controls (120.67 +/- 8.81 pmol/l vs 94.05 +/- 8.23 pmol/l; P = 0.02). There was no difference in the sex hormone binding globulin concentrations. However, following HCG stimulation the patients demonstrated a normal response with a 2-fold increase in testosterone. There was no difference in the testosterone and oestradiol levels of the patients and controls following HCG stimulation. This normal response in our patients demonstrates that the hypotestosteronaemia in Indian men with myocardial infarction is not due to a primary testicular dysfunction but probably is a result of increased aromatization of testosterone to oestradiol.