Potentially significant renal abnormalities were encountered in 7.3% of 151 symptom-free renal transplant donors and included renal cysts, cortical adenoma, ectopic and solitary kidney, and vascular abnormalities. Findings as they relat to donation of a kidney were important in 2.1% of patients and included solitary kidney and certain rare vascular variants rejected for technical reasons and danger of distal ureteral necrosis after transplantation.