The stump-tailed macaque (Macaca arctoides) appears to be a suitable biological model for human androgenetic alopecia. The expense, danger, and low availability compromise its value but macaques currently remain the model of choice. Rodent models, both testosterone induced alopecia and various xenograft approaches, show promise for elucidating fundamental information on normal and abnormal hair growth as well as serving as models to develop new therapies to treat hair loss.