Pulmonary embolism is associated strongly with proximal-vein thrombosis. We tested the hypothesis that recurrent venous thromboembolism is unlikely in the absence of proximal-vein thrombosis. We performed a prospective cohort study in 874 patients with suspected pulmonary embolism. On long-term follow-up of 371 patients with the following characteristics: (1) abnormal, non-high-probability lung scans, (2) off anticoagulant therapy, and (3) serial noninvasive test results negative for proximal-vein thrombosis, only 10 (2.7%; 95% confidence limits, 1.3% to 4.9%) had venous thromboembolism. By comparison, venous thromboembolism on follow-up occurred in 3 (1%) of 315 patients (95% confidence limits, 0.2% to 2.8%) with normal lung scans, and in 5 (7%) of 66 patients (95% confidence limits, 2.5% to 16.8%) with high-probability lung scans. Patients whose serial noninvasive test results were negative for proximal-vein thrombosis have a good prognosis without anticoagulant therapy.