Simvastatin is an effective hypocholesterolemic drug that inhibits cholesterol synthesis selectively in the liver, but could have potential side effects on the adrenal gland, ovary, and testis, as these three glands use cholesterol for their hormonal biosynthesis. In this report, we examined adrenal and sex steroids in 10 type IIA hypercholesterolemic patients (three with familial [FH] and seven with polygenic hypercholesterolemia) over a period of 1 year on simvastatin therapy in order to confirm in vivo its selective action. Furthermore, we evaluated the adrenal reserve by a corticotropin rapid test, before starting treatment and again at the end of the third month on 20 mg of simvastatin per day, then at the sixth and 12th month on 40 mg/d. There was a significant lowering of total cholesterol (TC) (-31%), low-density lipoprotein cholesterol (LDL-C) (-39%), and apolipoprotein (apo) B (-39%); no statistically significant differences were seen in cortisol response to the corticotropin test between baseline and simvastatin-treated patients. No variation of any sex steroid was observed in patients of either gender. We conclude that long-term therapy with high-dose simvastatin does not interfere with either adrenocortical function or sex hormone production.