Objectives Gonadal vein thrombosis is an uncommon but serious condition that can be fatal if it goes unnoticed. Up to 80% of cases occur in patients after delivery, hysterectomy, or lymphadenectomy for gynecological neoplasms. The objective of this study was to determine the incidence of gonadal vein thrombosis using computed tomography (CT) imaging at our center and to describe associated risk factors. Methods A retrospective, single-center, observational study was conducted at King Abdulaziz Medical City in Jeddah, Saudi Arabia. Data were collected for all patients diagnosed with incidental gonadal-vein-thrombosis using contrast-enhanced computed tomography imaging of the abdomen and pelvis between January 2005 and December 2017. We included all patients with incidental findings of gonadal vein thrombosis and excluded those with incomplete data. Results In total, 58/68,268 (0.08%) patients were included. Fifty-seven patients were females, and only one was male. The mean age (years) of the patients was 50.0±15.0 (range 4-87). Thirty-four patients (59%) had right gonadal vein thrombosis, 20 (34%) had thrombosis on the left side, and four (7%) had bilateral thrombosis. Nineteen patients (33%) had undergone pelvic surgery previously. Forty-four patients (76%) had a malignancy at the time of diagnosis. Forty-two patients (72%) were treated with anticoagulants after the diagnosis. Conclusion Gonadal vein thrombosis is a rare clinical entity with vague clinical presentation. The incidence in the oncology population is similar to the reported incidence in the obstetric population. Initiation of anticoagulation therapy is important to treat this condition and limit complications.