Acute-onset pelvic pain is an extremely common symptom in premenopausal women presenting to the emergency department. After excluding pregnancy in reproductive-age women, ultrasonography plays a major role in the prompt and accurate diagnosis of adnexal causes of acute pelvic pain, such as hemorrhagic ovarian cysts, endometriosis, ovarian torsion, and tubo-ovarian abscess. Its availability, relatively low cost, and lack of ionizing radiation make ultrasonography an ideal imaging modality in women of reproductive age. The primary goal of imaging in these patients is to distinguish between adnexal causes of acute pelvic pain that may be managed conservatively or medically, and those requiring emergency/urgent surgical or percutaneous intervention.