Parenteral and enteral nutrition have become major tools in the nutritional management of cancer patients perioperatively. The purpose of this article is to see if there is evidence from prospective controlled trials that parenteral and enteral nutrition preceding cancer surgery are of clinical benefit. From our investigation and from 8 other controlled, randomized clinical investigations the following conclusions can be drawn: Parenteral and enteral nutrition preceding cancer surgery improve nutritional parameters; Parenteral and enteral nutrition preceding cancer surgery may decrease postoperative morbidity and mortality, but this beneficial effect may not be limited to malnourished patients; If enteral nutrition can provide the same amount of proteins and calories as parenteral nutrition can, parenteral and enteral nutrition are equal with regard to clinical effects.