Nutritional concern is one of the most important issues to be addressed in the perioperative care given to gastrointestinal patients. Not at least, malnutrition may be detrimental and relate to postoperative morbidity. Perioperative nutritional management, integrated with other modern perioperative care policies, allows the establishment of multimodal strategies with an attempt to optimize the patients’ course of disease. The present review evaluates available data regarding pre- and postoperative nutrition, nutritional supplements, including immunonutrition, and their clinical role. It is to be concluded that pre- and postoperative prolonged fasting has no routine role in management. Instead, for example, early postoperative feeding administered perorally or enterally may reduce postoperative complications and length of hospital stay. There are also indications that perioperative immunonutrition may reduce postoperative infectious complications and length of hospital stay, though further studies in this field are needed.