A prospective study of 136 patients submitted to elective surgery for benign digestive tract pathology, submitted to elective surgery, has been done to evaluate the influences of the nutritional state and the perioperative transfusions on the development of postoperative infections. All patients were given a nutritional evaluation protocol based on anthropometric parameters, analytical data and delayed-type hypersensitivity skin tests (DHST). The criteria for undernourishment were a standard weight percentage lower than 90% and/or an albumin level lower than 3.5 g/dl. Transfusion indication was established at hemoglobin levels lower than 10 g/dl and/or hematocrit values below 30% with perioperative transfusion being considered as that which took place within three weeks prior to the surgery, that taking place during the surgery, and that which took place within the first 48 postoperative hours. The infections were qualitatively evaluated as wound infection, intraabdominal infection and respiratory infection, and quantitatively by means of the Elebeute and Stoner index. 32 of the patients (23.5%) presented undernourishment, and 18 of the patients (13.2%) were transfused. A total of 20 patients (14.7%) presented a postoperative infection. A significant association between under nourishment and infection has been shown (p =), as between transfusion and undernourishment (p < 0.001). Finally, we confirm that the combination of the factors undernourishment and transfusion leads a significance increase (f = 28,462, p < 0.001) of infectious complications.