['This study compared the efficacy of finasteride with placebo in the treatment of male pattern hair loss (androgenetic alopecia) in nine pairs of male identical twins.', 'In this randomized, double-blind, placebo-controlled, single-center study, one twin from each identical twin pair received finasteride 1 mg/day for one year while the other received placebo. Hair growth was evaluated from standardized clinical photographs, hair counts and patient self-assessment questionnaires. Serum dihydrotestosterone and testosterone levels were analyzed and adverse events recorded.', "Finasteride significantly improved hair growth at one year compared to placebo (p < 0.05) based on analysis of photographs of the vertex and superior-frontal scalp. These results were consistent with the hair count change measured in the finasteride group, which was superior (p < 0.05) to the change measured in the placebo group. Patient self-assessment demonstrated that treatment with finasteride, in comparison to placebo, led to improvements in scalp hair growth and patients' satisfaction with appearance of hair. No drug-related adverse events were reported during the study."] Does finasteride improve male pattern hair loss in a randomized study in identical twins?