A 22-year-old man with hypogonadotropic hypogonadism was receiving monthly intramuscular injections of testosterone replacement therapy. The patient refused to self-administer the injections because of discomfort, so the therapy was switched to testosterone patches. He experienced a pruritic, macular, erythematous rash underneath the reservoir area of two different transdermal formulations, which did not improve after pretreatment with topical corticosteroids. Eventually, he tolerated application of a testosterone gel and his serum testosterone levels returned to normal after 1 month of therapy. Commercially available and investigational testosterone products and therapeutic monitoring guidelines for androgen replacement are reviewed.