Purpose/Objective(s): Hepatocellular carcinoma with malignant portal vein occlusion carries an extremely poor prognosis. We assessed the efficacy and safety of three-dimensional conformal radiation therapy (3-D CRT) in the treatment of such patients. Materials/Methods: Thirty patients with HCC and PVTT were enrolled in the study and received radiation therapy in the form of 3-5 coplanner beams, all fields were treated daily at a dose fraction of 2 Gy, delivered as 5 fractions per week for 6 weeks to deliver a total dose of 60 Gy. Result: Sixteen patients (53.3%) showed response of the malignant thrombus to radiation therapy of whom, 8 patients (26.7%) showed complete resolution of the malignant thrombus and the other 8 patients (26.7%) showed partial resolution. Liver and gastrointestinal toxicity were rare and managed successfully. The median survival among the responders was 10.5 months significantly higher than 3.25 months for non-responders (p < 0.001). Conclusions: Three dimensional conformal radiation therapy is an efficient and well-tolerated technique to treat (in selected cases) PVTT. The responders showed a survival advantage. Author Disclosure: Y. Rostom: None. M.Y. El-Hasafy: None. A.S. El Yamany: None. S.E. Lashen: None.