A ruptured ovarian cyst can produce massive hemoperitoneum, with clinical symptomatology and sonographic features that closely mimic those of other disorders, in particular ectopic pregnancy. Considering the likelihood of both clinical and radiologic misdiagnosis, the radiologist should consider and pursue the diagnosis of a ruptured hemorrhagic ovarian cyst in a woman of child-bearing age who presents with pelvic pain and a large amount of complicated intraperitoneal fluid.