The accurate diagnosis of pulmonary embolism causes many problems. Clinical signs are non-specific, and ventilation-perfusion lung scanning has high sensitivity but variable specificity. In more than 90% of cases a pulmonary embolus is derived from deep venous thrombosis in the lower extremities. We have performed a prospective study to evaluate venography in the management of patients with suspected pulmonary embolism. A total of 169 patients were included in the study, and a ventilation-perfusion scan was performed in all cases. Forty-four (26%) patients had a normal scan and treatment was not given (group A). The other 125 (74%) patients, who had an abnormal scan, underwent bilateral venography. Venous thrombosis was demonstrated in 63 patients, and they were treated with oral anticoagulants for 3 months (group B). The remaining 62 patients, who showed no venous thrombosis, did not receive anticoagulant therapy (group C). During follow-up, 1 patient in group A, 3 patients in group B and 1 patient in group C developed a new deep venous thrombosis. One patient in group B suffered a pulmonary embolus. It is concluded that venography of the lower extremities can be of additional value in the management of patients with pulmonary embolism when the lung scan does not provide sufficient information.