Finasteride 1 mg/day is effective in the treatment of androgenetic alopecia (AGA). Our open-label study assessed the efficacy and safety of finasteride for the treatment of Taiwanese men with AGA. We enrolled 34 Taiwanese men (aged 18-40 yr) with AGA of modified Norwood/Hamilton scale (MNHS) grade II-V. In investigator assessments at 12 months, five of 21 subjects (23.8%) had two-grade improvement in MNHS grade and 12 of 21 subjects (57.1%) had one-grade improvement; the others remained at the same grade. In global photographic evaluation, five of 31 subjects (15.1%) had observable hair growth at 6 months and 11 of 21 subjects (52.4%) had observable hair growth at 12 months. Patient self-assessment of hair growth was favorable across all questions in the treatment course, more significantly at 12 months than at 6 months; nine of 21 subjects (42.9%) were satisfied with their overall appearance at 12 months. Serum prostate specific antigen levels had decreased by 23.4% at 12 months. Adverse effects, including abnormal liver function (5/34), were minimal, and the causal relationship with finasteride could not be established. Thus, in Taiwanese men with AGA, finasteride 1 mg/day for 1 year slowed the progression of hair loss and increased hair growth.