In the absence of proven effective pharmacologic therapy in acute pancreatitis, and given its simplicity, wide availability, and perceived safety, intravenous fluid resuscitation remains the cornerstone in the early treatment of acute pancreatitis. Herein, we will review the rationale of fluid therapy, critically appraise the published literature, and summarize recent studies.Several observational studies and small clinical trials have raised concern about the efficacy and safety of aggressive fluid resuscitation. Early aggressive fluid therapy among acute pancreatitis patients with predicted mild severity appears to have the highest benefit, whereas aggressive resuscitation in patients with predicted severe disease might be futile and deleterious. Lactated Ringer's solution is the preferred fluid type based on animal studies, clinical trials, and meta-analyses. There is a wide variation of fluid resuscitation approaches in current guideline recommendations, quality indicators, and worldwide practice patterns.There is lack of high-quality data that supports the use of early aggressive fluid resuscitation. Large, well designed, multicenter randomized controlled trials are needed to determine the optimal timing, fluid type, volume, rate, and duration of fluid resuscitation in acute pancreatitis.