The success of hemodialysis and peritoneal dialysis therapy is essentially dependent on adequate nutrition. Malnutrition represents one of the main factors in morbidity and mortality of dialysis patients. The main causes of malnutrition are insufficient energy intake, insufficient protein supply, loss of amino acids by dialysis, the uremic state of metabolism, catabolic stress of underlying diseases, and endocrinological disorders. For successful long-term chronic dialysis therapy, it is very important that patients be in an anabolic nutritional state when entering the dialysis program. In this paper, the nutritional needs of dialysis and peritoneal dialysis patients (fluid restriction, protein intake, energy supply, electrolyte balance, vitamin intake) are discussed to prevent the catabolic state.