Treatment of male pattern hair loss (MPHL) or androgenetic alopecia (AGA) with 5α-reductase inhibitor (5-ARIs) has been associated with sexual dysfunction including erectile dysfunction and loss of libido. This will be a multicenter, randomized, double-blind, placebo-controlled, parallel-group study to assess the impact of dutasteride treatment on sexual function as well as subject satisfaction with hair growth and quality of life in men with AGA. This study will consist of a Screening Visit, a 4-week Placebo Run-in Phase, a Treatment Phase of 48 weeks, and a subsequent Follow-up Visit after 4 weeks. The treatment phase will include 24 weeks of double-blind, placebo controlled treatment and 24 weeks of open-label treatment with dutasteride. An extended 6-month Follow-up Visit will be conducted for any individuals with a change in erectile function at the end of treatment.