Hypocaloric peripheral parenteral nutrition (HPPN) appears to be indicated in patients in a situation of moderate malnutrition who are to undergo a short period of fasting following surgery. Our aim was to determine the utility of the contribution of parenteral solutions of amino acids (AA) with limited caloric supply in the post-surgical patient, using different nutritional evaluation parameters. We examined 75 post-surgical patients who met at least two of the three criteria established as malnutrition: 1) albumin < 3 g/dl; 2) pre-albumin < 21 mg/dl; 3) bodyweight of less than 95% of the ideal weight. They were divided into four groups: a control group, of 15 patients undergoing standard fluid therapy; Group I, 20 patients with nutritional support of glucose +AA; Group II, 20 patients with glycerol +AA; and Group III of 20 patients with sorbitol-xylitol +AA. The most significant data encountered were a rapid recovery of short half-life proteins (pre-albumin and retinol), a less negative nitrogen balance, and a greater decrease of urinary 3-methylhistidine, when HPPN was used. A notable increase was also obtained in the majority of AAs and of the G and M immunoglobulin plasmatic figures in the groups treated. In terms of complications, a greater percentage of wound dehiscences appeared in the control group than in those treated (13.3 vs 5%) while, on the other hand, there was a higher incidence of catheter-induced phlebitis in groups undergoing HPPN. We conclude that HPPN is a valid nutritional support in post-surgical patients with more or less significant malnutrition, and when the gastro-intestinal tract cannot be used, for whatever reason, during the first week following the operation.