BACKGROUND: Gastrointestinal complications of solid organ transplantation have been well described, but little attention has been paid to colorectal disorders in particular. The purpose of this study was to identify the incidence and severity of colorectal complications among a large cohort of heart and lung transplant recipients. STUDY DESIGN: We reviewed the medical records of heart, lung, and heart-lung transplant recipients at a single institution between 1978 and 2004. Complications were identified based on need for consultation, endoscopy, or operation by a colorectal surgeon after transplantation. RESULTS: Of 1,012 patients who received transplantations (530 heart, 435 lung, 47 heart-lung), 56 patients (6%) required evaluation for 84 colorectal problems. Incidence of complications was 7% in lung transplant recipients, 6% in heart-lung transplant recipients, and 4% in heart transplant recipients. Forty-four events (52%) were considered major (diverticulitis, perforation, malignancy, and other) and 40 (48%) were minor (polyps, pseudo-obstruction treated medically or endoscopically, benign anorectal disease, and other). Twenty-three (27%) required colectomy and 9 (10%) necessitated anal operation. Thirty-six (43%) required less-invasive interventions (endoscopy, minor anorectal procedures, and other). Eighteen (21%) were treated with medical therapy alone. Six patients died from colorectal disease (7%). CONCLUSIONS: Colorectal complications are a considerable source of morbidity and mortality after heart and lung transplantation. These complications occur more frequently in patients who undergo lung and heart-lung transplantation as compared with heart transplantation alone.