The incidence of hepatocellular carcinoma (HCC) is increasing in the United States. Although liver transplantation is an effective means of treating selected patients, pretransplantation tumor progression may preclude some patients from undergoing transplantation. The aim of this study is to determine the safety and efficacy of percutaneous radiofrequency thermal ablation (RFA) in 33 consecutive patients with nonresectable HCC and advanced cirrhosis. Mean subject age was 57.2 +/- 10.6 years, mean Child-Turcotte-Pugh score was 7.0 +/- 1.4, and mean maximal tumor diameter was 3.6 +/- 1.1 cm. Using contrast-enhanced computed tomography and magnetic resonance imaging, 22 patients (66%) had a complete radiological response at 3 months post-RFA, whereas 11 patients (33%) had an incomplete radiological response. During follow-up, 18 patients (54%) experienced tumor progression and 9 subjects underwent repeated ablation for either residual disease or tumor progression. The overall actuarial patient survival rate of the 33 patients was 58% at 2 years, whereas the transplantation-free patient survival rate was 34% at 2 years. Fifteen of 23 transplant candidates were successfully bridged to liver transplantation after a mean post-RFA follow-up of 7.9 +/- 6.7 months. The extent of tumor necrosis in the explant varied, but no subjects had evidence of tumor seeding on post-RFA imaging, at liver transplantation, or in the explant. The 3-year actuarial posttransplantation patient survival rate was 85%. Two patients have developed posttransplantation recurrence, and both had microscopic vascular invasion in their explants. In summary, our data show that RFA is a safe and effective treatment modality for patients with advanced cirrhosis and nonresectable HCC. Although the ability of RFA to prevent or delay tumor progression requires further prospective study, its favorable safety profile and promising efficacy make it an attractive treatment option for liver transplant candidates with nonresectable HCC.