The effect of nutritional support in critically ill patients with sepsis has received much attention in recent years. However, many of the studies have produced conflicting results. As for all critically ill patients, nutritional support, preferably via the enteral route, should be commenced once initial resuscitation and adequate perfusion pressure is achieved. Where enteral feeding is impossible or not tolerated, parenteral nutrition (either as total or complimentary therapy) may safely be administered. Most positive studies relating to nutritional support and sepsis have been in the setting of sepsis prevention. Thus, the administration of standard nutrition formulas to critically ill patients within 24 h of injury or intensive care unit admission may decrease the incidence of pneumonia. Both arginine-supplemented enteral diets, given in the perioperative period, and glutamine-supplemented parenteral nutrition have been shown to decrease infections in surgical patients. Parenteral fish oil lipid emulsions as well as probiotics given in the perioperative period may also reduce infections in patients undergoing major abdominal operations, such as liver transplantation. There is little support at the present time for the positive effect of specific pharmaconutrients, in particular fish oil, probiotics, or antioxidants, in the setting of established sepsis. More studies are clearly required on larger numbers of more homogeneous groups of patients.