Congenital triangular alopecia is a rarely reported idiopathic congenital circumscribed alopecia. It presents with isolated patches of permanent alopecia involving the frontotemporal suture area of the scalp. It is necessary to differentiate it from other conditions such as alopecia areata in order to avoid prolonged treatment which may cause adverse side effects. We report a case of 7-year-old boy with congenital triangular alopecia. (Korean J Dermatol 2000;38(3)：421~423)