BACKGROUND: Surgical resection is the treatment of choice for most of the primary and secondary liver tumors, unfortunately, many patients are not suitable for resection. Several ablative alternatives have been employed for treatment; the most commonly used has been radiofrequency ablation. OBJECTIVE: To establish the safety and results of treatment with radiofrequency ablation (RF) of malignant liver tumors. MATERIAL AND METHODS: A retrospective review of clinical files of patients with malignant hepatic tumors treated with RF was performed. Epidemiological variables, selection criteria pre- treatment and morbidity and mortality related to the procedure were analyzed. Descriptive statistics were used. RESULTS: From September 2002 to August 2006, 30 patients were treated: eighteen females and 12 males with a median age of 62 years (range 41-83 years). Histologic type was as follows: 18 hepatocellular carcinomas; 10 metastatic tumors (four breast, four colorectal and two neuro- endocrine); one gallbladder carcinoma and one peripheral cholangiocarcinoma. Indications for ablative procedure were the presence of cirrhosis, poor functional reserve, bilobar disease, proximity to major vascular structures and patients with increased operative risk. The size of the lesion range from 2 to 20 cm (mean 5.6 cm) and the median time of ablation was 30.2 min (range 5-50 min). Two minor complications (6.6%) and no operative mortality were recorded. At 18 months of follow-up, 23 patients (76.6%) are still alive and seven patients have died for tumor progression. CONCLUSION: Radiofrequency ablation is a safe procedure that allows local control of the disease with satisfactory results, when the surgical resection is not feasible.