Tumor ablation by radiofrequency (RFA) is an appealing therapeutical strategy for the treatment of liver tumors (hepatocarcinoma and metastatic lesions) to be used as valid alternative to the surgical resection that often is appropriate and feasible in only a minority of patients. RFA induces the localised and controlled disruption of the tumor by heating the tissue causing its coagulative necrosis. Such therapy results as a pathogenic "noxa" for the body, inducing a strong inflammatory response. We wanted to ascertain whether the inflammatory response induced by RFA was similar in patients with hepatocarcinoma and in patients with liver metastasis. We considered body temperature, leucocyte counts at different time points as inflammatory parameters. We observed that RFA treatment produced the inflammatory systemic effects as expected (fever, increase of neutrophils) only in the patients with liver metastasis, while no such effect could be seen in the HCC patients. On the other hand the circulating monocytes increased after RFA in both groups of patients. These preliminary results suggest that RFA tratment can exert different effects on the immune system depending the etiopathogenesis of the treated neoplastic liver lesions.