Acute pelvic pain is defined as lower abdominal or pelvic pain of less than three months' duration. It is a common presentation in primary care. Evaluation can be challenging because of a broad differential diagnosis and because many associated signs and symptoms are nonspecific. The most common diagnoses in reproductive-aged women with acute pelvic pain are idiopathic pelvic pain, pelvic inflammatory disease, acute appendicitis, ovarian cysts, ectopic pregnancy, and endometriosis. Among postmenopausal women, cancer must be considered. Findings from the history and physical examination can point to likely diagnoses, and laboratory testing and imaging can help confirm. Women of reproductive age should take a pregnancy test. In early pregnancy, transvaginal ultrasonography and beta human chorionic gonadotropin levels can help identify ectopic pregnancy and spontaneous abortion. For nonpregnant women, ultrasonography or computed tomography is indicated, depending on the possible diagnosis (e.g., ultrasonography is preferred when ovarian pathology is suspected). If ultrasonography results are nondiagnostic, magnetic resonance imaging can be helpful in pregnant women when acute appendicitis is suspected. If magnetic resonance imaging is unavailable, computed tomography may be indicated.