Chronic renal failure was induced in rabbits by cauterization of one kidney and subsequent contralateral nephrectomy. After 3 and 8 months duration of uremia the 24-hour accumulation rate of radioactive cholesterol into the intima-media part of the thoracic aorta was measured. A significant higher uptake rate was found only in the 8 months uremic rabbits. In these rabbits macroscopic changes of the thoracic aorta were noted with dilatation, increased wall thickness and calcifications. In the 3 months uremic rabbits no morphological changes were seen. In the 8 months group of uremic rabbits the aortic concentration of calcium, phosphate and magnesium was 20-fold increased. In the 3 months group of uremic rabbits only the aortic calcium concentration was significantly increased. In none of the groups was the aortic cholesterol concentration increased. In rabbits long-term uremia induced aortic calcifications and an increased uptake rate of labelled plasma cholesterol but no net cholesterol accumulation could be demonstrated.