Purpose: To report the incidence and management of the radiofrequency ablation (RFA) complications in a single institution. Subjects & Methods: Three hundred and fifty patients undergoing RFA in a period of 4 years were included. RFA was applied percutaneously using ultrasound (US) guidance, and was performed using the expandible needle electrodes and generator (RITA 1500, RITA Medical System, Mountain View, CA, USA). The complications associated with RFA were recorded on the base of chart review. Results: A total of 396 tumors in 350 patients were treated with 431 RFA interventions. The median age was 62 years, and average tumor diameter was 2.8 cm. 313 lesions (79%) were primary hepatocellular carcinomas (HCC) (309) and cholangiocarcinomas (4), and 83 lesions (21%) were metastastatic tumors. All the RFA procedures were undertaken percutaneously using US guidance and monitoring. A total of 22 complications occurred in 19 patients (22/431, or 5.1%). These included: hematomas (7), asymptomatic bowel wall thickening (colon, duodenum) (4), thrombosis of portal vein branch (2), hepatic abscesses (2), intrahepatic biliary dilations (2), transient ileus (2), minor skin burn (1), intratumoral pseudoaneurysm (1), bloody ascites (uremic patients) (1). All but three complications (19/22) required only observation or conservative support. One patient with intratumoral pseudoaneurysm required further intervention and the other patients underwent abscess drainage. Low grade fever (37.0-38.4?) was reported within two days following the procedures in 14 interventions (8.1%). Fever higher than 38.4? in 3 interventions (3.0%) required administration of antipyretics and / or antibiotics. Conclusions: RFA rarely causes a clinically significant complication. Patient selection and careful preprocedural planning, and if possible, choice of most suitable RFA device / needle on a case-by-case basis are important to avoid complications.