End-stage kidneys are known to undergo cystic transformation in patients treated with long-term hemodialysis. Little has been published, however, on the occurrence of acquired renal cystic disease (ACD) in renal transplant recipients. The available clinical and histopathological data were gathered on 22 renal transplant recipients who had undergone either necropsy or nephrectomy. None of our patients exhibited cystic changes in their donor kidneys. However, 11 patients (50%) had ACD of the native kidneys while the remaining patients lacked ACD. The duration of dialysis prior to transplantation was significantly longer and the life of the functional transplant kidney was significantly shorter in the ACD group as compared to the noncystic group. The combined duration of ESRD (dialysis + transplantation), however, was comparable in the two groups. It thus appears that the presence of a functioning renal allograft somehow retards the evolution of cystic changes in the diseased native kidneys. 1 of the patients in the ACD group exhibited superimposed multifocal clear cell carcinoma of the affected kidney, while none of the patients in the noncystic group exhibited renal neoplasm.