Cancer chemotherapy after solid organ transplantation. To assess how well chemotherapy is tolerated after solid organ transplantation, we reviewed our experience at the Children's Hospital of Pittsburgh with five patients aged 1 to 12 years. Four patients had a liver transplant, indications for which were hepatoblastoma in two patients, hepatic failure secondary to Wilms' tumor chemoradiotherapy in one patient, and familial intrahepatic cholestasis in one patient. A fifth patient received a cardiac transplant for unresectable angiosarcoma of the right atrium. After transplant, chemotherapy was given for the treatment of the primary malignancy in four of the patients. The patient with familial intrahepatic cholestasis received chemotherapy for secondary lymphoproliferative disease that had not responded to the cessation of immunosuppression. All patients other than this patient were on immunosuppression with prednisone (0.5 to 2 mg/kg daily) and cyclosporine (to maintain serum levels at 800 to 1000 ng/ml radioimmunoassay) throughout the duration of chemotherapy. Courses of chemotherapy included one or more of the following agents: Adriamycin (Adr, 20 mg/m2 daily, three patients), Cyclophosphamide (Ctx, 1 gm/m2, one patient), cisplatin (CDDP, 90 mg/m2, one patient), Vincristine (Vcr, greater than 0.75 to 1.5 mg/m2, three patients), Actinomycin D (Act-D, 7.5 micrograms/kg, one patient), Ifosfamide (I, 1800 mg/m2, one patient) and Etoposide (VP-16, 100 mg/m2, one patient). All patients received greater than or equal to 3 courses (range, 3 to 9; mean, 5) of chemotherapy every 3 to 4 weeks. Dose reductions were made because of neutropenia in three patients but none were greater than 50%. Severe rejection was seen in one patient who had, however, manifested evidence of rejection prior to his first postoperative course of chemotherapy. No nephro or cardiac toxicity was seen. This preliminary experience suggests that chemotherapy is well tolerated after solid organ transplantation. 