Experience with the fibrinogen uptake test and the technetium Tc 99m albumin aggregated venous scan in 89 patients showed the latter to be adequate for simultaneous screening for plumonary embolism and venous thrombosis of the lower extremities and pelvis. Because the fibrinogen uptake test differentiated active from inactive venous thrombosis, it is indicated when anticoagulation is considered for patients with a history of thrombophlebitis and equivocal clinical findings of acute activity. It can also be used to monitor high-risk patients and to detect proximal propagation of thrombi. The results of the technetium venous scan were abnormal in 97% of patients with venous thrombosis and the fibrinogen uptake test detected 100% of patients with acute activity. Both tests react to different aspects of the thrombotic disease, thus complementing each other. Because of their reliability, indications for phlebography are now less frequent.