Pneumatosis intestinalis (PI) is an uncommon but important condition in which gas is found in a linear or cystic form in the submucosa or subserosa of the bowel wall. PI is a sign, not a disease; therefore, its relevance should be interpreted within the whole clinical context. PI has been found in several distinctive clinical settings: 1) in premature infants with necrotizing enterocolitis; 2) in adults with obstructive pulmonary disease; 3) in adults and children with a wide variety of associated conditions, including pyloric stenosis, jejunoileal bypass, progressive systemic sclerosis, transplantation, ischemic bowel, and drug therapy, particularly steroids, chemotherapy, and immunosuppression; 4) in adults as a primary benign problem; and 5) as an incidental finding in endoscopic mucosal biopsies. The two most important tasks of the physician include: 1) recognition of the entity of PI so that patients are not misdiagnosed and mismanaged as having malignancy or polyposis; and 2) differentiation of the benign variety, in which no intervention is indicated, from the life-threatening form, in which immediate surgery is necessary. Once life-threatening illnesses such as bowel necrosis, perforation, and infections are excluded, patients symptomatic from the cysts per se may be treated with oxygen and/or antibiotics. Because the reports of treatment of PI are at best anecdotal, the decision to treat and the treatment chosen should be carefully balanced with the risks.