Male pattern alopecia, or androgenetic alopecia, refers to the common patterned hair loss affecting many men. Male pattern alopecia is mediated by dihydrotestosterone (DHT), the potent form of testosterone, which induces miniaturization of androgen-sensitive hair follicles. There is a gradual conversion of terminal hairs into indeterminate and finally vellus hairs. The condition may profoundly affect self-esteem and impair psychosocial functioning for some men, and an association between early-onset male pattern alopecia and coronary artery disease has been shown.

The hair loss has a strong genetic basis. Onset is usually between the ages of 20 and 25 years, with prevalence and severity increasing with age. The incidence varies among ethnic groups. White people are the most commonly impacted, with 30% affected by 30 years of age, 50% by 50 years of age, and 80% by 70 years of age. A 2022 cross-sectional study of male balding patterns in people of color found variation between different races and ethnicities compared with White men: South Asian men had greater odds for vertex balding but lower odds for temporal balding; Chinese men were less likely to experience balding in any pattern; Black men also had lower odds for temporal, vertex, and severe balding (but to a lesser extent than Chinese men); and Black men were 4 times more likely to exhibit no or minimal balding.