This study was carried out on 30 patients with portal vein thrombosis to specify the nature of the thrombus whether malignant or benign, 24 patients were males(80%) and 6 were females (20%) with a mean age of 52.2 years.Grey scale U/S , tumor markers ,Doppler ultrasound and multidetector triphasic CT examination were performed to all patients and according to the grey scale U/S ,tumor markers and FNAC from suspicious thrombi 16 patients had malignant portal vein thrombi and 14 patients had benign thrombi. In the present study ,the specificity of color Doppler U/S for diagnosis of malignant PVT as regards the presence of intrathrombal pulsatile flow was 100% with 75% sensitivity, While the sensitivity of CT regarding thrombus neovascularity or thrombal arterial enhancement and portal washout was 87.5% with specificity 100% .