This study investigated the prognostic significance of portal vein tumor thrombosis (PVTT) response in hepatocellular carcinoma (HCC) patients treated with localized concurrent chemoradiotherapy (CCRT). We retrospectively analyzed 100 patients treated with CCRT for UICC Stage T2–4N0M0 HCC with PVTT between 2002 and 2011. The radiotherapy (RT) volume included both primary tumor and PVTT, and the median radiation dose was 45 Gy. Treatment response was evaluated for up to 6 months after RT. With respect to PVTT response to treatment, complete response (CR) and partial response (PR) were achieved in 14% and 48% of patients, respectively, yielding an objective response (OR) rate of 62%. PVTT size (≤3cm diameter) was associated with a higher rate of a CR (P = 0.001). The median overall survival (OS) was 11.6 months. Independent prognostic factors for OS were OR of the tumor to RT and a CR of the PVTT. Achieving an OR in both the tumor and the PVTT demonstrated a significant correlation with improved survival (P = 0.002). Progression of intrahepatic metastasis was affected not by CCRT but by the clinical features of the PVTT, particularly the initial PVTT site. PVTT response following CCRT seems prognostically significant. CR of the PVTT was associated with improved survival. Achieving an OR in both the tumor and PVTT was also associated with improved survival.