Postoperative complications in patients with disabling psychiatric illnesses or intellectual handicaps. A case-controlled, retrospective analysis. The purpose of this study was to quantitate the operative risk and costs encountered in the surgical treatment of institutionalized patients. Operative complications and duration of hospitalization for 200 institutionalized patients were compared with those in a control group of patients matched for age, sex, and type of operation drawn from the general hospital population. Postoperative complications occurred in 53 (26.5%) of the patients in the study group compared with 15 (7.5%) of the patients in the control group. Elective laparotomy was followed by a complication in 48% of institutionalized patients compared with 11.6% of matched controls. Emergency celiotomy carried a 75% complication rate in the study group. Atelectasis and pneumonia accounted for 50% of the postoperative complications and occurred with greatest frequency following intra-abdominal procedures. The median hospital stay for all institutionalized patients was 3 days more than for matched controls. A strategy for postoperative treatment is presented, with particular emphasis on prevention of pulmonary complications. 