To improve nitrogen balance and nutritional status, 10 paediatric patients (11.2 +/- 2.7 years; 28.5 +/- 5.1 kg) on regular haemodialysis (HD) for 25.3 +/- 1.2 months were treated with haemofiltration (HF) for 12.2 +/- 3.4 months. HF was prescribed using a urea kinetic model to ensure a pre-treatment blood urea nitrogen (BUN) of 130 mg/100ml. Urea generation rate (Gu) and protein catabolic rate (PCR) were computed by urea kinetics. Protein and calorie intake was assessed in the children on an unrestricted diet by analysis of 10 days' dietary records obtained every two months. During HF treatment a significant decrease of Gu and PCR was obtained and nitrogen balance increased in all the children.