The majority of patients (80%) admitted with acute pancreatitis recovers after a few days of bowel rest and intravenous fluids. However, some cases progress to a fulminant disease complicated by a severe systemic inflammatory response and multiple organ failure, a condition in which mortality is related to the degree of negative nitrogen balance. The goal of nutrition support in this situation is to cover the increased metabolic demands without stimulating pancreatic secretion and exacerbating the “autodigestion” that characterizes the condition. Although human and animal studies have shown conflicting results regarding the effect of composition and location of feeding on pancreatic enzyme secretion, there is consensus that total parenteral nutrition (TPN), given at moderate infusion rates, does not significantly stimulate secretion in humans and that enteral diets stimulate enzyme secretion unless delivered below the jejunum. Consequently, until recently TPN has been the standard of therapy. The fact that the cost and complications of TPN can often outweigh its benefits (catheter sepsis, hyperglycemia) has led to a series of recent controlled clinical trials of modified enteral diets in which the diet is delivered by nasojejunal tube. Results have demonstrated that enteral nutrition, with either elemental or polymeric formulas, was cheaper, safer, and at the same time more effective in reducing the systemic inflammatory response. The pathophysiologic explanation for these observations needs further investigation.