Malnutrition is frequent in dialysis patients and it increases the mortality risk in this setting. There are many causes of malnutrition including protein metabolism impairment, amino acid and nutrient losses in dialysate, dialysis-induced muscle catabolism, metabolic acidosis, increased energy expenditure, resistance to anabolic hormones, comorbidities, oxidant stress and inflammation whose mechanisms are not identified well. Inflammation and malnutrition are associated with vascular complications frequently observed in dialysis patients. Daily nutrient needs have been established from nitrogen balance studies. The recommended intakes are 1,2 g/ kg/day for proteins, and 35 Kcal/kg/day for energy. Food intake in dialysis patients remain far below these recommendations in most of the studies, mainly because of anorexia caused by inflammation and the uremic state. Dialysis dose or frequency increase food intake. Evaluation of the nutritional status relies on biological parameters and anthropometrics, with food intake records. Nutritional scores, established from these data, are well correlated with patient outcomes. Malnutrition treatment includes counselling, and suppression of all inflammation sources. Appetite stimulants have been seldom used in this setting. Oral supplements may be efficient Intradialytic parenteral nutrition in hemodialysis patients and amino acid-enriched dialysate in peritoneal dialysis improve nutritional parameters of malnourished patients but their efficiency to improve patient survival is questioned. Adequate nutrition is an important challenge for dialysis patient outcome. Nutritional status must be regularly assessed and treated if necessary. Close collaboration between dialysis and dietetic staffs remains essential to handle this challenge.