BACKGROUND The treatment of malnutrition, frequently present in elderly dialysis patients, is important to promote better quality of life and rehabilitation. The aim of this study was to assess the impact of prolonged use of intradialysis parenteral nutrition (IDPN) as a strategy for malnutrition in elderly haemodialysis patients. METHODS Twenty-eight elderly patients (non-diabetic, age over 70) on chronic haemodialysis for at least 2 years were evaluated. Ten consenting patients were treated with IDPN containing glucose, essential amino acids, and lipid emulsion during the course of regularly scheduled dialysis treatments for approximately 1 year. Nutritional evaluation using seven parameters (anthropometric measurements such as body mass index, triceps skinfold thickness, mid-arm circumference, mid-arm muscle circumference, and albumin, transferrin, and total lymphocyte count) was performed at various intervals on patients with IDPN and 18 patients without IDPN. The plasma amino-acid profile and dietary protein calorie intake were also determined. RESULTS In patients receiving IDPN, significant increases in serum albumin and transferrin concentrations and total lymphocyte count in peripheral blood smears paralleled increases in protein-calorie intake beginning after 3 months of treatment and remained favourable throughout the study period. Anthropometric data started to improve significantly after 6 months of treatment. Patients without IDPN had gradual decreases in all parameters during the study period. A significant increase in essential amino acids and a significant decrease in 3-methyl-histidine were observed in patients with IDPN and a further decrease in essential amino acids was observed in patients without IDPN. CONCLUSIONS Prolonged use of IDPN prevents muscle protein catabolism and promotes body protein and fat accumulation. IDPN appears to be effective in malnourished elderly haemodialysis patients.