Finasteride, a type 2-selective 5alpha-reductase inhibitor, was approved in 1997 as the first oral pharmacologic therapy for the treatment of men with androgenetic alopecia (AGA; male pattern hair loss). Originally developed for the treatment of men with benign prostatic hyperplasia (BPH) at a dose of 5 mg/day, finasteride has a well-established, excellent safety profile. Subsequent studies demonstrated that finasteride was an effective treatment for men with AGA at an optimal dose of 1 mg/day. This report summarizes the published peer-reviewed literature on the use of finasteride in the treatment of men with AGA, including the data on long-term (5 years) use of finasteride in a placebo-controlled clinical trial environment.