The results of subcutaneous lateral internal sphincterotomy for chronic fissure-in-ano were analyzed in a series of 60 patients operated upon over a period of two years. Immediate relief from pain with painless first bowel movement was accomplished in 97 per cent of the patients with very low morbidity rates. All patients were treated on an outpatient basis and had a minimum follow-up of two years without any recurrences. The incidence of sphincter dysfunction is very low and is usually only temporary.