The acute abdomen accounts for up to 40% of all emergency-surgical hospital admissions and is considered in the differential in the more than 7 million visits to the emergency department annually for abdominal pain in the United States. A large percentage of these cases are secondary to perforation or impending gastrointestinal perforation. Gastrointestinal perforation causes considerable mortality and usually requires emergency surgery.Rapid diagnosis and treatment of these conditions is essential to reduce the high morbidity and mortality of late-stage presentation. Successful treatment requires a thorough understanding of the anatomy, microbiology, and pathophysiology of this disease process and in-depth knowledge of the therapy, including resuscitation,antibiotics, source control, and physiologic support.