Malnutrition is a common and significant problem in patients with cancer. Enteral nutrition support is an important therapy and is preferred over parenteral nutrition in the setting of a functional gastrointestinal tract. Familiarity with the indications for enteral support, the choice of an enteral access device, and the selection of an enteral formula are critical for the care of patients with cancer and malnutrition. Enteral nutrition has proven efficacy in patients receiving radiation to the head and neck, those with persistent dysphagia, and critically ill patients with impaired gastric emptying. Placement of feeding tubes through the nose or percutaneously provides a mechanism to deliver nutrients when proximal obstructions or oropharyngeal dysphagia prevent adequate oral intake. Direct access to the jejunum can be safely obtained endoscopically and is very useful in patients who require enteral nutrition support following a gastrectomy or esophagectomy or have impaired gastric emptying. Standard polymeric formulas are appropriate for most patients. Specialized formulas designed to enhance immune function may decrease infectious complications but do not improve survival.