AIM: To investigate the treatment efficacy of radiofrequency ablation (RFA) of hepatic malignant tumor and the relevant complications.METHODS: A total of 338 patients with 763 hepatic tumors underwent ultrasound-guided RFA (565 procedures).There were 204 cases of hepatic cellular carcinoma (HCC)with 430 tumors, the mean largest diameter was 4.0 cm.Of them, 48 patients (23.5％) were in stages Ⅰ-Ⅱ (UICC Systems) and 156 (76.5％) in stages Ⅲ-Ⅳ There were 134 cases of metastatic liver carcinoma (MLC), with 333metastases in the liver, the mean diameter was 4.1 cm,the liver metastases of 96 patients (71.6％) came from gastrointestinal tract. Ninety-three percent of the 338patients were treated using the relatively standard protocol. Crucial attention must be paid to monitor the abnormal changes in ultrasound images as well as the vital signs of the patients to find the possible hemorrhage and peripheral structures injury in time. The tumors were considered as ablated completely, if no viability was found on enhanced CT within 24 h or at 1 mo after RFA. These patients were followed up for 3-57 mo.RESULTS: The ablation success rate was 93.3％ (401/430tumors) for HCC and was 96.7％ (322/333 tumors) for MLC. The local recurrence rate for HCC and MLC was 7.9％ (34/430 tumors) and 10.5％ (35/333 tumors),respectively. A total of 137 patients (40.5％) underwent 2-11times of repeated ablations because of tumor recurrence or metastasis. The 1st, 2nd, and 3rd year survival rate was84.6％, 66.6％, and 63.1％, respectively;the survival rate from 48 patients of Ⅰ-Ⅱ stage HCC was 93.7％, 80.4％,and 80.4％, respectively. The major complication rate in this study was 2.5％ (14 of 565 procedures), which consisted of 5 hemorrhages, 1 colon perforation, 5 injuries of adjacent structures, 2 bile leakages, and 1 skin burn.CONCLUSION: RFA, as a minimally invasive local treatment,has become an effective and relatively safe alternative for the patients of hepatic malignant tumor, even of advanced liver tumor, tumor recurrence, and liver metastases. Knowledge about possible complications and their control may increase the treatment efficacy and help to promote the use of RFA technique.