RF interstitial thermal ablation (RFA) has yielded satisfactory results in the treatment of both primary and secondary hepatic tumors with no serious complications. We describe our experience with 163 patients who had this treatment. We used the RITA Needle electrode (model 30; four hooks, model 70; seven hooks) in 101 cases, the LeVeen Needle electrode in 32 cases and the Cool-tips type electrode in 30 cases. Post treatment tumor necrosis was evaluated by dynamic CT or SPIO MRI in all cases. The mean number of RFA sessions to complete tumor nodule treatment was 1.2 (1 session; 85%, 2 sessions; 12%, more than 3 sessions 3%). The mean complete necrosis area of single ablation with RITA Needle electrode was 31.3 +/- 6.1 mm x 29.6 +/- 5.5 mm. Seventy-two patients were followed up for 6-24 months (means; 15.2 months). Of these patients, 4 (5.6%) showed local recurrence. No fatal or major complications related to the treatment or to the diagnostic procedure were observed. In one of 163 patients, a moderate-to-large pleural effusion was documented after RFA, and resolved by drainage. In conclusion, RF interstitial thermal ablation of hepatic tumor is a safe and effective technique for hepatic tumors.