The substitution of protein deficiency by a standardized dosage of 48...60 g human albumin and 160 g amino acids divided over 4 days is hardly less effective as the substitution by the same dosage of amino acids alone. Insignificant differences of the preoperative und postoperative effect of the substitution therapy in patients with tumors of esophagus or stomach and colorectal cancer are discussed and seem to confirm the conclusion to perform the parenteral substitution of protein deficiency economical better only by the administration of amino acid solutions. The additional administration of non-protein calories in the meaning of parenteral nutrition seems to be dispensable if the simultaneous enteral alimentation satisfies these requirements. The relative substitution dosage of amino acids should not fall below 2,5 g . kg-1 divided over 4 days.