The aim of this prospective study was to evaluate the efficacy of color duplex scanning in comparison with plebography in patients with clinically suspected deep vein thrombosis of the legs. The group was of sixty patients. The tests were both positive in 51 limbs and negative in 8 limbs. In a case of below-knee thrombosis, color-duplex was negative while phlebography was able to show small localized thrombosis. The sensitivity of color-duplex was 98%, its specificity and positive predictive value 100% and its negative predictive value 88.8%. In conclusion, color-duplex is as effective as phlebography in detecting deep vein thrombosis above knee.