Review of our experience with pneumatosis intestinalis has allowed identification of three major clinical groups of patients. In each of these groups, the etiology of pneumatosis intestinalis usually can be identified, and it frequently has an ominous prognosis. Treatment should be directed to the underlying condition when possible, and hence must be individualized. Those patients who would be categorized as Group I can simply be kept under observation. Patients in Group II might obtain relief from breathing increased concentrations of oxygen. For patients in Group III vigorous therapeutic measures generally are necessary to ensure survival. The increasing use of mechanically controlled ventilation and positive end-expiratory pressure may be contributing to the incidence of pneumatosis intestinalis. The ileus sometimes observed in these patients may accompany or precede the development of intramural air, a condition identifiable on roentgenographic examination. Awareness of the possible presence of intramural air may help in identifying patients who may not need operation. But even when roentgenographic examination has confirmed the presence of intramural air, abdominal exploration still may be necessary to rule out a diagnosis of perforated viscus. We hope that these concepts and our emphasis upon individualization of treatment may improve the prognosis for patients who have pneumatosis intestinalis.