Background and Aim: Percutaneous thermal ablation using radiofrequency ablation (RFA) and microwave ablation (MWA) are both widely available curative treatments for hepatocellular carcinoma. Despite significant advances, it remains unclear which modality results in better outcomes. This meta-analysis of randomized controlled trials (RCT) and observational studies was undertaken to compare the techniques in terms of effectiveness and safety. Methods: Electronic reference databases (Medline, EMBASE and Cochrane Central) were searched between January 1980 and May 2014 for human studies comparing RFA and MWA. The primary outcome was the risk of local tumor progression (LTP). Secondary outcomes were complete ablation (CA), overall survival, and major adverse events (AE). The ORs were combined across studies using the random-effects model. Results: Ten studies (two prospective and eight retrospective) were included, and the overall LTP rate was 13.6% (176/1298). There was no difference in LTP rates between RFA and MWA [OR (95% CI): 1.01(0.67-1.50), P=0.9]. The CA rate, 1- and 3-year overall survival and major AE were similar between the two modalities (P>0.05 for all). In subgroup analysis, there was no difference in LTP rates according to study quality, but LTP rates were lower with MWA for treatment of larger tumors [1.88(1.10-3.23), P=0.02]. There was no significant publication bias or inter-study heterogeneity (I 2 <50% and P>0.1) observed in any of the measured outcomes. Conclusion: Overall, both RFA and MWA are equally effective and safe, but MWA may be more effective compared to RFA in preventing LTP when treating larger tumors. Well-designed, larger, multicentre RCTs are required to confirm these findings.