To determine the safety and cost-effectiveness of outpatient preoperative bowel preparation with polyethylene glycol-electrolyte lavage solution, we retrospectively analyzed 726 cases of colectomy done by colon and rectal surgeons between July 1987 and July 1991. Included were 319 patients who had elective segmental or total abdominal colectomy with primary anastomosis. Patients who required protective proximal stoma were excluded. Patients requiring emergency surgery, colostomy closure, and restorative proctocolectomy were excluded. Patients were separated into two groups equally matched by age, sex, procedure done, and comorbidity: 145 had bowel preparation as outpatients and 174 as inpatients. Both groups had similar numbers of days hospitalized, days receiving nothing by mouth, and days requiring nasogastric intubation or gastrostomy tube, as well as similar postoperative complications. There was one wound infection, one anastomotic leak, and one death in each group. Cost of outpatient preparation was approximately $40. Cost of inpatient preparation, including a semiprivate room, was approximately $400. Outpatient preparation with polyethylene glycol-electrolyte lavage solution and oral antibiotics before elective colon resection can be done with equivalent safety and at a substantial cost savings.