Objectives: To investigate whether radiofrequency (RF) ablation with low power (LP) or maximal power (MP) for hepatocellular carcinoma (HCC) can achieve optimal ablation and fewer adverse effects. Methods: RF ablation was performed with MP in 101 patients (129 tumours) and with LP in 46 patients (61 tumours). MP RF ablation used power of .120 W. RF power below this was designated as LP. Clinical outcomes were also analysed in subgroups of highrisk tumours near the bile duct and blood vessels. Results: Primary effectiveness was achieved in 91.8% in the LP group and 89.9% in the MP group (p50.795). 1 and 2-year local tumour progression rates were 28% and 30%, respectively, in the LP group, and 24% and 29%, respectively, in the MP group (p50.70). 1 and 2-year survival rates were 98% and 98%, respectively, in the LP group, and 93% and 90%, respectively, in the MP group (p50.216). The MP group had more adverse effects, with post-RF ablation syndrome, asymptomatic pleural effusion and ascites, than the LP group (20% vs 39% in the MP group; p50.027); however, there was no significant difference in major complication rates (6% in the MP and LP groups; p50.497). Among the patients with high-risk tumours, RF ablation using MP vs LP was comparable in primary effectiveness (91.7% vs 95.2%; p50.618), local tumour progression (42.9% vs 29.2%; p50.304) and overall complications (5% vs 8%; p50.618). Conclusion: RF ablation with LP and MP are comparable in clinical outcomes but considerably fewer adverse effects were encountered in the LP group.