Female patients with varying grades of acne were examined to determine whether free testosterone levels were a more sensitive indicator of hyperandrogenism than total testosterone values. Of 24 women with acne studied, four were found to have elevated total testosterone levels, whereas 11 had elevated free testosterone levels. Twenty-four age-matched female control subjects without acne, hirsutism, or irregular menstrual cycles all had normal free and total testosterone values. The mean concentration of free testosterone in the patients with acne was 1.035 ng/dL, while in the control subjects it was 0.54 ng/dL. Other than hirsutism in three patients with acne with elevated free testosterone levels, there were no morphologic clues identified to determine which patients with acne are more likely to have abnormal free testosterone levels. The free testosterone level did not correlate with the type, distribution, or severity of the acne present in the patients.