Acute pancreatitis (AP) is an acute inflammatory process of the pancreas, with variable involvement of other organ systems. It is a common disease, with an incidence of 29.3 per 100,000 population per year in New Zealand. In the severe form, AP carries a mortality of up to 20-54%. There is no specific treatment for acute pancreatitis and current therapy is supportive. Intravenous fluid therapy forms a cornerstone of this therapy. There is a lack of evidence about the optimal fluid therapy. Data contradict each other with the latest evidence indicating that there is increased mortality if excessive fluid is given. There is an urgent need for a randomised controlled trial to establish the evidence-base for goal-directed fluid resuscitation in acute pancreatitis. The proposed full study will be the first randomised trial investigating the use of organ-specific markers to optimise fluid therapy in AP.