The development of malignancies in renal transplant recipients is well documented. Typically, these are cutaneous tumors or lymphomas. During the past 5 years, we have encountered six patients with documented carcinomas of the gastrointestinal tract, which developed after these patients received renal transplants. These carcinomas developed at an average of 10 years (range 2-16 years) after renal transplantation. There were three carcinomas of the colon, and one each of the esophagus, stomach, and anal canal. In many instances, the patients had examinations prior to transplantation which were normal. Several surveys of transplant recipients indicate there is an increased incidence of gastrointestinal tract malignancies after transplantation. These studies also recommend that screening of the gastrointestinal tract in long-term transplant recipients be performed. Since these patients are often imaged in the radiology department, radiologists must be aware of this possible complication.