Malnutrition is a very important problem in children with ESRD on peritoneal dialysis. Examinations were conducted on 20 children (9 girls, 11 boys), 10 children were treated continuous ambulatory peritoneal dialysis (CAPD) and 10 automated peritoneal dialysis (APD). Anthropometric and serum biochemical parameters were examined. Dialysis adequacy by KT/V, SCCr, PCR were described. The most significant malnutrition was observed in youngest children with lowest BMI values and significant muscle and fat mass deficiency. Increased protein catabolic rate (PCR) in children under 6 years old was an important factor leading to malnutrition.