Local tumor recurrence after thermal ablation of hepatocellular carcinoma (HCC) can impact on overall survival and are very closely linked to partial treatment of the primary lesion or to potential microvascular invasion or satellite micronodules located close to the main lesion. The diagnosis of these liver metastases close to the primary lesion on CT and MRI is difficult and their incidence, number and spread throughout the liver correlates with diameter of primary tumor. Tumor diameter is currently the key factor to predict whether or not thermal ablation of HCC will be complete or not. It has now been shown for monopolar radiofrequency ablation that this therapy alone is sufficient to effectively treat single HCCs<3cm in diameter provided that liver micrometastases are not present. If the HCC is>3cm in size, multifocal or in the case of tumor recurrence, overall survival and recurrence-free survival results are better if monopolar radiofrequency ablation is combined with hepatic trans-arterial chemoembolization. The timing of this combination of treatments probably influences its effectiveness on tumor and tolerability and remains to be assessed.