1. Nutritional status and leucine turnover has been measured in ten patients with chronic renal failure before the onset of continuous ambulatory peritoneal dialysis (CAPD) and after 3 months treatment, and in five normal subjects.
2. Somatic muscle protein reserves, as judged by anthropometry and measurement of total body potassium, showed no significant changes after 3 months treatment and were not significantly different from normal.
3. Visceral protein reserves, as judged by serum albumin and plasma amino acids, showed a significant fall after 3 months CAPD and were also lower than in normal subjects.
4. Protein turnover was lower in uraemic than in normal subjects, but the balance between synthesis and breakdown was significantly higher and was maintained after 3 months on CAPD.