The response to acute isotonic saline loading (1800 ml in 3 h) was assessed in 12 normotensive and 11 hypertensive renal transplant recipients. Both groups had similar renal function, daily urinary excretion of sodium and doses of steroids. The natriuretic response to saline was not affected in hypertensive transplants and changes in blood pressure, renin and aldosterone were identical in both groups. Similar correlations between presaline fractional excretion of sodium (FENa+) and the FENa+ obtained during saline were found in normotensive and hypertensive patients. These results demonstrate that recipients of renal transplants who are hypertensive do not show an exaggerated natriuresis in response to saline, thus suggesting that normal kidneys carry their characteristics when transplanted in a new environment. The role of renal denervation remains unclear.