Renal transplantation is the optimal mode of therapy for patients with end-stage renal disease; the results are even better with living related donors. This procedure, therefore, favours the recipients, but what are the consequences for the donor? At our Department, between 1973 and 1996, 1325 kidney transplantations were performed, 78 from living, related donors (5.89%). We decided to follow up these patients and investigate the function of the remaining kidney and also their current general health status. Thirty donors (38.4%) were investigated. Of these, 25 of had normal blood pressure and 5 were hypertensive, needing antihypertensive treatment. The average age was higher in the hypertensive group (60.2/53.25 years). The time interval since transplantation was longer in the hypertensive group than in the normal one. We carried out a scintigraphy of the kidney with Tc-99mMAG-3. The mean value of the glomerular filtration rate calculated from the MAG clearance was 98.1 ml/min and this value is higher than half of the normal isotope clearance value, i.e. higher then the expected value for a single kidney. We conclude that no impairment of renal function is observed in the living, related kidney donors. In 16.66% a mild hypertension developed. With isotope investigation we found hypertrophy of the remaining kidney. Thus, after a correct preoperative assessment, unilateral nephrectomy has no long-term consequences in healthy donors.