ABSTRACT Background A single-arm expanded treatment efficacy and safety study of TACE in Japan and Korea was conducted to confirm the reproducibility of the results in the phase III study carried out by Llovet et al., which showed a significant survival advantage of TACE, compared with conservative treatment, for unresectable HCC. Methods Patients with unresectable HCC who had no indications for curative treatment and who had not received prior therapy for HCC were enrolled. The patients underwent TACE using an emulsion of epirubicin HCl or doxorubicin HCl and Lipiodol, followed by the injection of gelatin sponge particles. The treatment was repeated on an as-needed basis. The primary end point was the 2-year survival rate, and the secondary end points were the incidence and grade of adverse events and the response rate. Results The study accrued 102 patients enrolled at 27 institutions in both countries between January 2008 and January 2009, but three patients withdrew their informed consent. The 2-year survival rate of the 99 evaluable patients was 75.0% (95% CI, 65.2–82.8%). The median time-to-progression and the median overall survival period were 7.6 months and 3.1 years, respectively. Among the 99 evaluable patients, 42 (42%) achieved a complete response and 31 (31%) had a partial response, and the response rate was 73% (95% CI: 63–82%) using the modified response evaluation criteria for solid tumors. The major grade 3–4 toxic effects were an increased AST level (35%) and an increased ALT level (36%), thrombocytopenia (12%), and abdominal pain (4%); all other toxic effects were generally transient. Conclusion In Japan and Korea, TACE exerted a marked favorable efficacy in patients with unresectable HCC who were not suitable for curative treatment, and this treatment modality may be regarded as a standard therapy for unresectable HCC.