This article describes four patients with perforated gastroduodenal ulcers related to smoking "crack" cocaine. All patients came to the hospital with acute abdominal pain; only one patient had a history of ulcer disease. Only one patient had an elevated white blood cell count, and two patients had depressed white blood cell counts. In three patients, the x ray showed that pneumoperitoneum was present. Upon surgical exploration of the abdomen, all patients were found to have extensive peritoneal contamination. Operative repair consisted of omental patching with or without primary closure of the perforation. A history of cocaine smoking should be sought in patients with unexplained abdominal pain or pneumoperitoneum. In patients with acute abdominal pain and a history of smoking cocaine, a perforated gastroduodenal ulcer may be present, despite normal or low white blood cell counts and the lack of pneumoperitoneum on x-ray examination.