Two hundred and thirty five consecutive patients with a life threatening complication of peptic ulceration, who either died or required emergency surgery, have been studied over a 36 month period. Seventy eight of these high risk patients died; 25 at home, 19 in hospital without surgery and 34 postoperatively. Ninety eight patients had bleeding ulcers, 132 perforated ulcers and five had both bleeding and perforated ulcers. One hundred and forty one of these 235 patients (60%) were taking a non-steroidal anti-inflammatory drugs (NSAID) and the individual agents have been listed. The overall incidence of NSAID use in a hospital control group was 9.9%. The first sign of an ulcer was a life threatening complication in 58.2% of patients taking a NSAID. Nearly 80% of all ulcer related deaths occurred in patients using an anti-inflammatory agent. Patients using these drugs were older, with more pre-existing medical conditions and had larger ulcers than those not taking NSAIDs. The mortality associated with a peptic ulcer complication in patients taking a NSAID was more than twice that in patients with no such drug history. There appears to be a relationship between the development of a life threatening complication of peptic ulceration and NSAID ingestion. Much of the associated mortality and morbidity may be potentially avoidable.