One hundred and thirty-four patients admitted to the medical emergency ward due to suspect deep venous thrombosis (DVT) were examined. The uptake of intravenously injected porcine 99Tcm-plasmin was estimated in both legs. Thereafter, phlebography was performed using a high osmolar contrast medium. All phlebographies were evaluated independently. All patients with negative phlebography were examined clinically after 3-5 days. The plasmin test and phlebography were repeated when called for. The sensitivity of the plasmin test was 100% and the specificity 51% when compared to phlebography. The extension of the DVT as demonstrated by the plasmin test was similar to that determined by phlebography. Post-phlebographic thrombosis was very rare. It is concluded that 99Tcm- plasmin test is a rapid method, convenient to the patient and well suitable as a screening test. The results indicate that a negative plasmin test excludes DVT while a positive test necessitates additional examination by phlebography.