Patients with free intraperitoneal air usually undergo emergency surgery. Some of these patients will have no identifiable perforation, for instance those with pneumatosis cystoides intestinalis. This is a rare condition characterized by multiple intramural gas cysts in the gastrointestinal tract. The most common symptoms are meteorism, excessive flatulence, diarrhoea, abdominal pain, passage of mucus per rectum, or rectal bleeding. A case of pneumatosis cystoides intestinalsis is described. Plain abdominal radiographs showed distended bowel with free intraperitoneal air and intramural gas collections. At laparotomy, multiple intramural cysts were found, but no perforation or obstruction. The symptoms resolved after laparotomy, and the patient was discharged after a few days. The aetiology and pathogenesis of pneumatosis cystoides intestinalis are unknown, although deficient hydrogen metabolism and gasforming bacteria that penetrate the mucosal barrier may be involved. If needed, hyperbaric oxygen therapy is the treatment of choice. Surgery is indicated only in fulminant cases.