A recent study demonstrated that hirsute women with irregular menses had higher levels of serum androgens than hirsute women with regular menses. To investigate this finding, we measured total testosterone, biologically active testosterone, free testosterone, androstenedi-one, dehydroepiandrosterone, and dehydroepiandrosterone sulfate in 51 hirsute women with regular menses and compared the levels found to those found in 28 hirsute women with oligomenorrhea. There was no significant difference in the degree of facial hirsutism between the two groups. Oligomenorrheic women had significantly higher levels of free testosterone ( p<0.02) and biologically active testosterone ( p<0.05). The other androgens did not differ significantly between the two groups. The free fractions of testosterone are the metabolically active forms of the hormone and their levels are a function of the rates of production and clearance of testosterone that are elevated in states of hyperandrogenism. This study confirms that hirsute women with oligomenorrhea have higher levels of free and biologically active testosterone than those with regular menses.