Pilonidal disease is apparently much commoner in the military service than in civilian life. This is because (a) pilonidal sinus is a disease primarily of young men, and (b) conditions of military life are conducive to the start of symptoms. A total of 77,637 soldiers1 were admitted to Army hospitals for pilonidal disease from 1942 to 1945. This is the equivalent of five infantry divisions. These figures do not include 9000 other cases of pilonidal cyst admitted primarily for other disease or hundreds of thousands of outpatient visits.1 Prior to World War II the accepted treatment for pilonidal disease in the Army was excision, and this persists in civilian practice today. The Army, however, has come to accept a much more conservative treatment.2 Although the rate of hospital admissions has increased slightly (3.05 per 1000 vs. 3.24 per 1000), the average number of days spent in the