Acute pancreatitis is a polymorphic disease with dynamic imaging characteristics and a multitude of possible complications established on crosssectional imaging. Effective utilization of imaging in patients with acute pancreatitis requires a profound knowledge of the natural course of disease and familiarity with the subtypes and complications of acute pancreatitis. Imaging, primarily computed tomography (CT), in acute pancreatitis has various aims. CT can confirm the diagnosis or provide an alternative diagnosis, identify the etiology of pancreatitis, detect local pancreatic and extrapancreatic complications, offer prognostic information, and guide therapeutic interventions. Conventional radiography, ultrasound (US), endoscopic retrograde cholangiopancreatography (ERCP), and magnetic resonance imaging (MRI) have important complementary roles in the assessment and management of patients with acute pancreatitis. This chapter will discuss the role of imaging in the assessment of etiology of acute pancreatitis. Also, imaging characteristics of those with predicted severe disease and those with pancreatic and extrapancreatic complications directly influencing individual patient management will be addressed.