In the Commentary "Study of the Food and Drug Administration Files on Propecia: Dosages, Side Effects, and Recommendations" published in the March 1999 issue of the ARCHIVES, Frankel1 challenges the decision by the Food and Drug Administration to approve finasteride, 1 mg (Propecia; Merck & Co Inc, Whitehouse Station, NJ), for the treatment of men with male pattern hair loss. Frankel argues that the dose of Propecia is "far higher than the level measured as necessary for inhibition of the conversion of testosterone to DHT [dihydrotestosterone]," based on serum and scalp DHT levels we measured in balding men treated with finasteride for 6 weeks.2,3