Androgenetic alopecia In men, or male pattern baldness, is recognized increasingly as a physically and psychologically harmful medical condition that can be managed effectively by generalist clinicians. This article discusses the clinical manifestations, epidemiology, physical and psychosocial importance, pathophysiology, diagnosis, and management of androgenetic alopecia in men. Androgenetic alopecia affects at least half of white men by the age of 50 years. Although androgenetic alopecia does not appear to cause direct physical harm, hair loss can result in physical harm because hair protects against sunburn, cold, mechanical injury, and ultraviolet light. Hair loss also can psychologically affect the balding individual and can Influence others' perceptions of him. A progressive condition, male pattern baldness is known to depend on the presence of the androgen dihydrotestosterone and on a genetic predisposition for this condition, but its pathophysiology has not been elucidated fully. Pharmacotherapy, hair transplantation, and cosmetic aids have been used to manage male pattern baldness. Two US Food and Drug Administration-approved hair-loss pharmacotherapies-the potassium channel opener minoxidil and the dihydrotestosterone synthesis inhibitor finasteride--are safe and effective for controlling male pattern baldness with long-term daily use. Regardless of which treatment modality is chosen for male pattern baldness, defining and addressing the patient's expectations regarding therapy are paramount in determining outcome.