Hypertrichosis is hair growth that is abnormal for the age, sex, or race of an individual, or for a particular area of the body. Recognized forms of hypertrichosis are reviewed. Hirsutism, which is male-pattern hair growth in a female or child, is not included in this review. Hypertrichosis is categorized as congenital or acquired, and regional or generalized. Methods of managing hypertrichosis are also briefly reviewed. (J Am Acad Dermatol 2003;48:161-79.) Learning objective: At the completion of this activity, participants should be familiar with the causes of hypertrichosis and treatment modalities.