Purpose: To determine the efficacy and safety of transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC) and main portal vein (MPV) invasion. Materials and Methods: This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively assessed the electronic medical records of patients in whom HCC with MPV invasion was newly diagnosed from January 2004 to December 2007 at a single tertiary medical center. Patients with decompensated hepatic function were excluded. Outcomes of patients treated with TACE were compared with those of patients given supportive care according to Child-Pugh class. Results: One hundred twenty-five patients (104 men and 21 women; mean age, 55.7 years; age range, 33.4-83.0 years) were included. The median overall survival was 3.7 months (range, 0.2-33.3 months). Eighty-three of the 125 patients (66.4%) were treated with TACE and 42 (33.6%) received supportive care. Repeated TACE showed significant survival benefits compared with supportive care in patients with Child-Pugh class A (median survival, 7.4 months vs 2.6 months, respectively; P < .001) and class B (median survival, 2.8 months vs 1.9 months, respectively; P = .002) disease. Results of multivariate analysis showed that treatment with TACE (hazard ratio, 0.263; 95% confidence interval [CI]: 0.164, 0.424; P < .001) and Child-Pugh class A status (hazard ratio, 0.550; 95% CI: 0.368, 0.822; P =.004) were independent predictive factors of a favorable outcome. There were no procedure-related deaths within 4 weeks after TACE, and patient morbidity was 28.9% (24 of 83 patients). Conclusion: TACE can be performed safely and may improve the over-all survival of patients with HCC and MPV invasion.