Tumor-related complications after intestinal transplantation in children have been principally EBV driven post-transplant disorders. We describe the clinical course of a child, with a diagnosis of microvillus inclusion disease who received a liver and intestine allograft at the age of 9 months. His postoperative course was significant for multiple episodes of acute intestinal allograft rejection and eventually the development of post-transplant lymphoproliferative disorder (PTLD), which resolved. At 8 yr post-transplant he presented with masses in the intestine allograft mesentery and in the right lobe of the allograft liver, biopsy of which revealed a relatively undifferentiated tumor, suggestive of a carcinoma. In situ hybridization for X and Y chromosomes, revealed his tumor to be of donor origin. Treatment included debulking of the mesenteric mass with segmental enterectomy of the intestinal allograft, and stopping his immunosuppression for a period of 4 months; this resulted in complete resolution of his malignancy. Immunosuppression with tacrolimus and steroids was restarted because of intestinal allograft rejection; he died suddenly of unknown causes at 17 months post-diagnosis of carcinoma. The severely immunosuppressed state produced in this patient allowed for the development of an unusual donor derived carcinoma, which resolved spontaneously with withdrawal of immunosuppression. The mechanism of such regression of tumor may be related to restitution of immunologic competence, but is yet to be determined.