During the past year, two important large-scale studies have been published that demonstrate that preoperative parenteral nutritional support improves the clinical outcome of severely malnourished patients. Both trials highlighted the importance of targeting the use of total parenteral nutrition on those patients most likely to benefit. With regard to the composition of parenteral nutrition solutions, our knowledge of lipid emulsions, particularly regarding their effects on the immune system, has expanded significantly. The infusion of a mixture of medium-chain triglycerides and long-chain triglycerides rather than long-chain triglycerides alone may be beneficial in certain circumstances. More evidence has accumulated in favor of the addition of glutamine to parenteral nutrition solutions, and it appears that free glutamine may, after all, be safely added to parenteral nutrition solutions. From a practical point of view, advances in the prevention of thrombophlebitis have enabled peripheral parenteral nutrition to increase in popularity.