Idiopathic thrombocytopenic purpura, an immune-mediated disease, usually has a relatively benign clinical course. Bleeding manifestations are mostly mucocutaneous and mild. Massive haemorrhages requiring transfusions or other interventions are rare, unless platelet counts are extremely low or other complicating conditions coexist. The rupture of an ovarian follicle is a very common benign condition in women of the reproductive age group. Any associated bleeding is unlikely to be significant, unless there is an underlying severe haemostatic derangement. We describe a 24-year-old Filipino woman presenting with severe abdominal pain and intra-abdominal haemorrhage requiring laparotomy, which revealed massive haemoperitoneum and a ruptured ovarian follicle. She had thrombocytopenia secondary to previously undiagnosed idiopathic thrombocytopenic purpura. This case illustrates how a combination of two otherwise common and benign clinical entities can result in a rare and potentially life-threatening event.