Purpose: The purpose of this study was to assess the efficacy and safety of radiofrequency ablation (R F A) to treat hepatic metastasis in patients with colorectal carci-noma. M aterials and M ethods: Between M ay 1999 and July 2002, a total of 45 tumors in 24 patients with colorectal cancer were treated with R FA. Thirteen patients received systemic chemotherapy after the R FA procedure. The ablation was performed percutaneously under ultrasound guidance using cool-tip or expandable electrodes and an RF generator. The medical records as well as the C T scan results taken every 3 months were retrospectively reviewed. R esults: The median follow-up duration of the surviving patients was 11.7 months (4.6～32.2 months). C omplete tumor necrosis was achieved in 17 patients (70.8%) on an immediate (＜24 hrs) C T scan. The median survival was 17.1 months. The 1-and 2-year survival rates were 80.5 and 25.8% , respectively. In a univariate analysis, complete necrosis, tumor size and post-R FA chemotherapy were significant factors for survival. N ineteen of the 24 patients developed a recurrence or progressed (79.2%). The median progression free survival was 5.5 months. There were no treatment related deaths or serious adverse effects, with the exception of one case of respiratory failure. C onclusion: These results suggest that R FA is a well-tolerated and effective method to treat hepatic me-tastasis in colorectal carcinomas. (C ancer R esearch and Treatment 2004;36:128-131) 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏 Key W ords: R adiofrequency ablation, H epatic metas-tasis, C olorectal neoplasm