Résumé : Relatively little is known about the progression of androgenetic alopecia (AGA; male pattern hair loss) in untreated men. We evaluated the long-term (5-year) progression of AGA in men treated with placebo in a controlled clinical trial setting. We analyzed pooled data over 5 years from two replicate studies with finasteride 1 mg/day in men with predominantly vertex-pattern AGA. Each study consisted of an initial 1-year, randomized, double-blind, placebo-controlled base study and four consecutive, 1-year, double-blind, placebo-controlled extension studies. Change over time in scalp hair growth was evaluated by four predefined endpoints: scalp hair counts; assessment of standardized clinical photographs by an expert panel; investigator clinical assessment; and patient self-assessment. All four predefined endpoints demonstrated progressive scalp hair loss in men receiving placebo over the 5-year study period, with a loss of 239 hairs from baseline (26.3% decline in hair density) measured in the target area at 5 years (p < 0.001 vs. baseline). Similarly, visible progression of scalp hair loss was demonstrated by global photographic assessment, with 75% of placebo patients rated as worsened from baseline at 5 years. We found that scalp hair loss continued in a progressive manner over a 5-year period in placebo-treated men with AGA.