Acute abdomen is a condition that demands urgent attention and treatment. The acute abdomen may be caused by an infection, inflammation, vascular occlusion, or obstruction. The patient will usually present with sudden onset of abdominal pain with associated nausea or vomiting. Most patients with an acute abdomen appear ill. The approach to a patient with an acute abdomen should include a thorough history and physical exam. The location of pain is critical as it may signal a localized process. However, in patients with free air, it may present with diffuse abdominal pain. Auscultation may reveal absent bowel sounds and palpation may reveal rebound tenderness and guarding, suggestive of peritonitis. The causes of an acute abdomen include appendicitis, perforated peptic ulcer, acute pancreatitis, ruptured sigmoid diverticulum, ovarian torsion, volvulus, ruptured aortic aneurysm, lacerated spleen or liver, and ischemic bowel.