For patients with hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT), the survival benefit of transarterial chemoembolization (TACE) compared with conservative treatment largely remains controversial. The objective of this study was to determine whether TACE confers a survival benefit to patients with HCC and PVTT, and to uncover prognostic factors. Between July 2007 and July 2009, a prospective two-arm nonrandomized study was performed on consecutive patients with unresectable HCC with PVTT. In one arm, patients were treated by TACE using an emulsion of lipiodol and anticancer agents ± gelatin sponge embolization. In another arm, patients received conservative treatment. A total of 164 patients were recruited for the study (TACE group, n = 84; conservative treatment group, n = 80). Patients in the TACE group received a mean of 1.9 (range, 1-5) TACE sessions. The overall median survival for all patients was 5.2months, and the 12- and 24-month overall survival rates were 18.3% and 5.6%, respectively. The 12- and 24-month overall survival rates for the TACE and conservative groups were 30.9%, 9.2%, and 3.8%, 0%, respectively. The TACE group had significantly better survivals than the conservative group (P < 0.001). On subgroup analysis of segmental and major PVTT, the TACE group also had significantly better survivals (P = 0.002, P = 0.002). The treatment type, PVTT extent, tumor size, and serum bilirubin were independent prognostic factors of survival on multivariate analysis. TACE was safe and feasible in selected HCC patients with PVTT and it had survival benefit over conservative treatment.