Plasma amino acid profiles along with hemoglobin, hematocrit, albumin, protein, blood urea nitrogen and serum creatinine values for ten patients undergoing abdominal operations were studied before operation and for 16 days there-after at different intervals. Six patients in the control group were studied in a similar manner. From the observations obtained, we concluded that total amino acid valued are a more sensitive reflection of patient nutrition in both the preoperative and postoperative periods. In future, total amino acid levels may become part of the nutritional assessment of a patient undergoing an operation. The histidine levels in plasma remain low for the longest period of time, an indication of a great need for histidine. Hence, greater attention should be paid to the histidine content of a diet or solution administered parenterally, or both. In addition, branched chain amino acids, alanine, glycine, cystine, arginine, lysine, tryptophan and threonine are required in greater quantity than the other amino acids as a result of the increased catabolism and partial starvation of the patients postoperatively. In formulation hyperalimentation solutions, an increased need for these amino acids should be kept in mind.