This article describes the case of a 36-year-old woman. who presented with a 2-day history of abdominal pain and nausea. Laboratory investigations revealed no abnormalities. Ovarian vein thrombosis was detected on ultrasound examination, and computed tomography of the pelvis and abdomen confirmed this finding. The patient was placed on anticoagulant therapy with unfractionated heparin and warfarin. Within 40 days her thrombosis improved. Laboratory testing for coagulation disorder revealed nothing abnormal. Ovarian vein thrombosis must be recognized and treated early to reduce the risk of serious complications. This case of idiopathic ovarian vein thrombosis underlines the importance of including this condition in the list of differential diagnoses for abdominal pain.