Lichen sclerosus et atrophicus, a disease said to be rare in boys, was found in 14 of 100 prepubertal boys undergoing elective circumcision for disease of the foreskin. The clinical features of the disease, in particular the acquired scarring phimosis of the tip of the prepuce, were distinctive. Extragenital involvement was not found. Scarring phimosis in boys must be considered to be one of the most common manifestations of lichen sclerosus et atrophicus.