1. 1. The value and practicability of the preoperative and postoperative administration of a special dietary supplement were studied in fifty-seven surgical patients. Nine other surgical patients were employed as controls. 2. 2. The dietary supplement (gerilac) ∗ ∗ Gerilac, manufactured by The Bordon Co., Prescription Products Division, New York, N. Y. is a spray-dried mixture of whole milk, skim milk, dried brewer's yeast fortified with riboflavin concentrate, vitamins A and D concentrate from fish liver oils, irradiated ergosterol, ascorbic acid, niacinamide, monosodium phosphate and iron citrate. The milk ingredients are so formulated as to provide a high protein and low fat content. 3. 3. The periods during which the dietary supplement was administered ranged from two weeks to three months. In fifteen cases the dietary supplement was given daily during the preoperative period. In thirteen of these cases the patient was also given the supplement for two to three weeks postoperatively. 4. 4. In forty-two instances the dietary supplement was administered postoperatively and during convalescence (but not preoperatively), beginning in most cases three or four days after operation. 5. 5. All patients were carefully studied. Blood determinations included hemoglobin value, red cell count, differential white blood cell picture and blood calcium. Reaction to anesthesia, operation and chemotherapy was noted as well as general clinical course and rate of convalescence as evidenced by wound healing, gain in weight and strength and subjective response. 6. 6. In all of the fifty-seven patients receiving the dietary supplement the clinical course was gratifyingly smooth and convalescence was comparatively rapid, i.e., more rapid than in the control patients. Adverse effects of anesthesia, surgical manipulation and chemotherapy were minimal. 7. 7. Patients receiving the dietary supplement preoperatively showed gains in appetite, weight and strength, experiencing at the same time a sense of improved well being. 8. 8. Administered postoperatively and during convalescence the dietary supplement aided in reducing the patient's discomfort and in promoting rapid convalescence. The progress of the controls was definitely less satisfactory. 9. 9. The blood determinations reflected the favorable clinical results associated with the routine provision of a diet high in biologically potent protein, with unusually high levels of vitamins and minerals. Hemoglobin values and red cell counts were increased as was the blood calcium in most cases in which it was subnormal. At the same time the white blood cell pictures showed marked trends toward normal. 10. 10. The gains in weight associated with dietary supplementation were taken to be the most impressive evidence of efficient tissue fabrication resulting from a constantly favorable nutritional status.