Unprovoked venous thromboembolism (VTE) may be the earliest manifestation of cancer. According to recent studies, approximately 5% of patients with unprovoked VTE will be diagnosed with cancer within the first year of follow-up. Although screening extensively at the time of VTE diagnosis is attractive for clinicians, current clinical guidance documents suggest only a limited cancer screening strategy. The authors describe a rare case of Krukenberg tumor of the ovary arising from a primary gastric adenocarcinoma whose first sign was an unprovoked venous thrombosis of the upper extremity.