Daily dialysis have showed excellent results because a higher frequency of dialysis is more physiological and it decreases the fluctuation of liquid, solutes and electrolytes. Improvement of certain causes of anorexia such as postdialysis fatigue, reduction in fluid overload, uremic milieu, medium and large-sized molecule removal could be observed with daily dialysis. The aim of this study was to evaluate nutritional parameters when thrice weekly on-line hemodiafiltration (OL-HDF) were switched to daily OL-HDF. 24 patients have been studied. Eight patients, 6 males and 2 females, mean age of 65.9 +/- 14 years, on thrice weekly 4 to 5 hours OL-HDF were switched to 2 to 2.5 hours six times per week. Dialysis parameters were the same in both periods and only frequency and dialysis time were changed. Other sixteen patients, mean age of 68.4 +/- 14 years, were a control group which dialysis parameters were maintained. Clinical and biochemical outcome were carried out over twelve months. Daily OL-HDF group: Dry weight increased from 67.8 +/- 8 kg at baseline to 68.5 +/- 8 kg after three months, 69.3 +/- 8 kg after six months (NS), 69.5 +/- 8 kg after nine months (p < 0.05) and 70.8 +/- 8 (p < 0.01) after one year. Mean nPCR increased from 0.93 +/- 0.2 g/kg/d on baseline to 1.18 +/- 0.3 after three moths (P < 0.0-5), 1.13 +/- 0.2 after six months (NS), 1.06 +/- 0.2 after nine months (NS) and 1.10 +/- 0.2 after twelve months (NS). There were no significant changes in serum protein, albumin, prealbumin, transferrin, total cholesterol, HDL-c, LDL-c and triglycerides (TG). There were no changes in control group. Mean dry weight was 62.3 +/- 9 kg at baseline and 62.1 +/- 10 kg after one year. Mean nPCR was 0.97 +/- 0.2 g/kg/d on baseline and 1.03 +/- 0.2 g/kg/d after one year. Neither there were changes in serum protein, albumin, transferrin, total cholesterol, HDL-c, LDL-c and TG. Improvement in nutrition status has been observed with the change from thrice weekly OL-HDF to short daily OL-HDF. Increased appetite and protein intake was accompanied by a dry body weight increase of three kg after twelve months.