Dietary protein and calorie intake, protein catabolism and peritoneal kinetics were measured in 97 CAPD patients to establish the effect of peritoneal glucose absorption on appetite and survival. There was a large variability in the number of calories obtained from the dialysate, mean 5.89 cal/kg (median 5.43 cal/kg), with a skewed distribution, due to the increased requirement for hypertonic solutions by patients with more rapid glucose absorption and poor ultrafiltration. On average calories derived from peritoneal absorption accounted for 19% of the total energy intake which in itself was well below that recommended. Patients with > 6 cal/kg, obtained from the dialysate (top 20th percentile, n = 19) were compared with those with < 6 cal/kg, but no significant differences in oral protein or calorie intake, protein catabolism or total calorie intake were found. Age, body mass index (BMI) and KT/V were also similar in both groups. Patients were followed-up prospectively for a minimum of 24 months and a comparison made of actuarial survival. Patients with high peritoneal calorie intake tended to survive longer but this was not significantly different (p = 0.25). This study suggests that calories derived from the peritoneum in CAPD patients do not suppress appetite, provide a useful and significant proportion of the total energy intake, that does not cause excessive obesity or have a negative effect on patient survival.