Aggressive nutrition has been reported to improve growth parameters in children undergoing peritoneal dialysis. The current study reports the effect of a program of aggressive nutrition, started in 1/1988, on catheter-related infection rates in children undergoing chronic peritoneal dialysis. A combination of high calorie foods, supplements, "candy bar diets", and, when necessary, modular gastrostomy feedings, to provide 3-4 gm/kg/d and 100-120 kcal/kg/d was used. Peritonitis and catheter infection rates were assessed. A total of 37 pediatric patients underwent peritoneal dialysis from 1/1986-7/1990, with a total cumulative experience of 596 patient months. The peritonitis rate decreased from 1 episode/5.53 patient-month in 1987 to 1 episode per 46 patient-month in 1990. There was no significant effect on the catheter infections or the number of admissions/patient month. However, there was a 55% decline in the number of hospitalization days/patient month (p less than 0.01). The decrease in the peritonitis rate was independent of the modality of peritoneal dialysis or the usage of ultraviolet connecting devices. In 10 patients followed sequentially, the peritonitis rate was less (1 episode/23.5 patient months) after gastrostomy tube placement and feedings than before gastrostomy tube placement (1 episode/8.28 patient months) (p less than 0.01). There were no significant differences in serum albumin or total protein levels between the two observation periods. We conclude that adequate nutrition may play a role in decreasing the peritonitis rate in children maintained on peritoneal dialysis and speculate improved white cell function as a possible underlying mechanism.