The diagnosis of puerperal ovarian vein thrombophlebitis by computed axial tomography (CAT) scan is reported. The characteristic finding, ie, a soft tissue mass with a diameter of 2 cm and length of 14 cm, extending from the uterine cornua to the level of the renal vein, can be seen by CAT scan. The near total resolution of the mass on follow-up CAT scan confirmed successful treatment with antibiotics and heparin. Observation of these findings will allow future cases to be definitively diagnosed and treated without invasive procedures.