There are no reports on the effects of pharmacologic treatment on the likelihood of developing further visible hair loss in men with androgenetic alopecia (AGA). Our objectives were to examine whether finasteride 1 mg treatment decreases the likelihood of developing further visible hair loss in men with AGA. We conducted an analysis of global photographic assessment data from two Phase III trials in which 1553 men with AGA received finasteride 1 mg/day or placebo for up to 5 years. Finasteride 1 mg treatment led to a 93% decrease relative to placebo in the 5-year likelihood of developing further visible hair loss (95% CI: 89-97%; p < 0.001). We conclude that, in men with AGA, treatment with finasteride 1 mg/day over 5 years led to a marked and sustained decrease in the likelihood of developing further visible hair loss.