Abdominal X-ray interpretation depends upon the assessment of the bowel gas pattern, solid organ outlines, a search for abnormal calcification and a review of the skeleton. The erect X-ray shows multiple dilated gas-filled loops of bowel with several air-fluid levels. Computed tomography (CT) is the imaging investigation of choice for patients with suspected small bowel obstruction (SBO). Ultrasound has high specificity in diagnosing appendicitis, but it is operator dependent. Ultrasound is frequently used to investigate patients with acute abdominal pain, but overlying bowel gas often limits the ability to visualize the entire pancreatic gland. CT has good specificity in diagnosing pancreatitis, although in up to one-third of patients with acute pancreatitis, no detectable change in the size or appearance of the pancreas is evident. Early identification of patients with potentially severe acute pancreatitis is important, as patients with delayed transfer to intensive care units have higher mortality.