Abdominal pain is among the most frequent ailments reported in the office setting and can account for up to 40% of ailments in the ambulatory practice. Also, it is in the top three symptoms of patients presenting to emergency departments (ED) and accounts for 5-10% of all ED primary presenting ailments. There are several common sources for acute abdominal pain and many for subacute and chronic abdominal pain. This article explores the history-taking, initial evaluation, and examination of the patient presenting with acute abdominal pain. The goal of this article is to help differentiate one source of pain from another. Discussion of acute cholecystitis, pancreatitis, appendicitis, ectopic pregnancy, diverticulitis, gastritis, and gastroenteritis are undertaken. Additionally, there is discussion of common laboratory studies, diagnostic studies, and treatment of the patient with the above entities.