SUMMARY: The metabolism in vitro of testosterone by normal human skin has been studied and the results have been compared with those obtained in two cases of testicular feminization. The predominant metabolite was 5α-dihydrotestosterone followed by androstenedione, androsterone, and 5α-androstanedione. Suprapubic skin from patients with testicular feminization metabolized testosterone in a completely normal manner. There was no evidence to support the view that a failure to produce an essential metabolite of testosterone is responsible for the condition of testicular feminization.