Acute abdominal pain is a very common presentation of patients in the emergency department. The spectrum of pathologies range from benign and self-limiting to high morbidity and potentially life-threatening. Although clinical history, physical examination, and laboratory tests are critical for evaluation, imaging plays a key role in many clinical scenarios. Imaging can help clinicians’ diagnostic confidence, as many acute abdominal pathologies present with nonspecific symptoms. Furthermore, imaging can evaluate for complications, some of which can be life-threatening. Lastly, imaging can help guide management, especially with regard to whether the patient needs urgent surgery. In this chapter, we review common causes of acute abdominal pain: appendicitis, small bowel obstruction, diverticulitis, colitis, mesenteric ischemia, and acute gastrointestinal bleeding. In each section, we start with a brief discussion of epidemiology and clinical features. Next, we compare different imaging modalities, with specific recommendations from the American College of Radiology appropriateness criteria. The specific imaging techniques are detailed. Lastly, we discuss common imaging findings, as well as important associated complications.