Unrecognized abdominal injury remains a distressingly frequent cause of preventable death following blunt trauma. Peritoneal signs are often subtle, overshadowed by pain from associated injury, and masked by head trauma or intoxicants. The initial management of the patient with blunt abdominal trauma should parallel the primary survey of airway, breathing, and circulation. Diagnostic peritoneal lavage remains the cornerstone of triage in patients with life-threatening blunt abdominal trauma. The only absolute contraindication to the procedure is an existing indication for laparotomy. Computed tomography is useful as a complementary diagnostic tool in selected patients, and it is the critical test for guiding nonoperative management of known intraperitoneal trauma. Routine ancillary tests for potentially occult injuries include nasogastric-tube placement for ruptures of the left diaphragm, Gastrografin contrast study for duodenum perforation, and pyelography for urologic injury. Ultrasonography may become a valuable tool in the initial assessment of the injured abdomen. Ultimately, the most important principle in the management of blunt abdominal trauma is repeat physical examination by an experienced surgeon.