The influence of sympathectomy (SE) by s.c. administration of 6-hydroxydopamine (10 mg/100 g b.m. daily from the 1st up to the 4th day of life) on the age dependent development of the renal excretion of water and electrolytes was tested by means of diuresis experiments in conscious rats. Immediately after SE natriuresis occurs as a consequence of denervation. Already on the 10th day of life this denervation diuresis disappears due to several compensatory mechanisms and 10 to 55 day old rats excrete less sodium than control animals of the same age. The potassium excretion is also diminished in 20 to 55 day old rats. The results show -- that the typical age course of water and electrolyte excretion is not altered by SE, -- that adrenergic influences are of importance for the renal function in rats, and -- that the consequences of the sympathectomy can be fully compensated in the kidney too.