Radio frequency ablation (RFA) of hepatocellular carcinoma has proved to be useful in local control of tumor. A few data on survival after treatment are available in literature. The aim of the study was to evaluate factors related to survival and to identify different classes of risk after radio frequency ablation. Ninety-eight cirrhotic patients with 145 hepatocellular carcinomas were treated with radio frequency ablation from January 1998 to May 2004. In 55 patients, cirrhosis was in Child-Pugh class A, and in 43, in class B. Tumor was single in 60 and multiple in 38; mean tumor number was 1.5 (range 1-3). Tumor size ranged from 1.5 to 6.0 cm, mean 3.8 cm. Mean follow up period was 24.9 months. Radio frequency ablation was performed with expandable type needle with percutaneous approach under real-time ultrasound guidance. For statistical analysis, univariate and multivariate analysis were performed. Complete ablation of the tumor was achieved in 85.5% of lesions. Survival, 1 and 3 years, was 76.7 and 36.6%, respectively. Univariate analysis showed that Cancer of the Liver Italian Program (CLIP) score, tumor growth pattern, alpha-fetoprotein level, and complete tumor necrosis, were factors significantly related to poor survival. Multivariate analysis identified that factors related to poor survival were alpha-fetoprotein level >100 ng/ml, Child-Pugh class B, and incomplete tumor necrosis with a hazard ratio of 4.0, 2.7, and 3.8, respectively. After complete ablation, median survival was 38 months in patients with Child-Pugh class A cirrhosis and alpha-fetoprotein level < or =100 ng/ml, 22 months for patient with Child-Pugh class B cirrhosis and alpha-fetoprotein < or =100 ng/ml, and 9 months for patient with Child-Pugh class A cirrhosis and alpha-fetoprotein >100 ng/ml (P < 0.01). Complete necrosis and absence of residual tumor positively affect survival after RFA. In patients with Child-Pugh A cirrhosis and alpha-fetoprotein level < or =100 radio frequency, ablation have results, 55% after 3 years, that are comparable to those of surgical resection. Patients with Child-Pugh B cirrhosis and/or alpha-fetoprotein >100 ng/ml showed less satisfactory results, and in these patients, multimodality treatment or other treatments should be considered.