Acute pancreatitis (AP) is one of the most common diseases of the gastrointestinal tract. The most common cause of AP is gallstones and alcohol. Other causes include medications, infectious agents and metabolic causes. Recent studies have identified obesity as an etiological factor and a marker of poor prognosis in AP. Nonalcoholic fatty liver disease (NAFLD) is a condition characterized by deposition of lipids in the hepatocytes. Obesity, particularly metabolic obesity, is associated with an increased incidence and severity of AP. NAFLD is a marker of metabolic obesity, which can be easily diagnosed, with the help of initial abdominal ultrasound (AUS) routinely performed in all patients with AP upon admission to assess a biliary aetiology. Many recent studies have identified obesity as a marker of poor prognosis in AP. Results from meta-analysis show that obesity (defined as BMI>30) was associated with significantly higher incidence of systemic and local complication and higher rate of mortality from AP. Several independent studies have also confirmed this observation.