A simplified, robust, clinical assessment, used in conjunction with a d-dimer assay, has been developed to identify patients with a low risk of deep vein thrombosis. These patients did not undergo radiological examination. The protocol has been used by junior doctors in a district general hospital with a predominantly elderly population. Four hundred and thirty-one patients with potential deep vein thrombosis of the lower limb were assessed using this method and 98 (22·7%) did not require further investigation. Of these, one was admitted 5 months later with a pulmonary embolus. None of the other patients subsequently required admission for a thromboembolic event or died during a minimum of 3 months follow-up.