The accuracy of our clinical vascualr laboratory was evaluated. Sixty-nine limbs (55 patients) were examined clinically for thrombophlebitis. All of these patients were then evaluated using segmental plethysmography and Doppler ultrasound techniques. Each limb was then studied with venography. In 57 of the 69 (82.6%) limbs evaluated, measurement of the maximum venous outflow accurately reflected the venographic findings. Doppler augmented venous sounds were correct when compared to venography in 77.6% of limbs. In the 59 limbs that exhibited clinical signs of deep venous thrombosis, only 35.6% had venographic confirmation of the diagnosis. The clinical vascular laboratory provides an accuracy of diagnosis of deep venous thrombosis not achieved by clinical examination. If both segmental plethysmography and Doppler ultrasound were negative, it was very unlikely that deep venous thrombosis had occurred.