To compare the effectiveness and complications of various thermal ablative therapies through reviewing the available literature. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was used to report this systematic review. Our PICO (patient group-intervention-comparator-outcomes) question: In patients with unresectable colorectal cancer liver metastasis (CRCLM), what are the comparative effectiveness and complication rates of the various thermal ablative therapies? All study designs published between 2000 and 2012 considered. Search results were screened in duplicate to determine eligible studies. A customized "risk of bias" assessment tool was utilized. Asymmetry of the funnel plot and heterogeneity were quantified. Representative forest plots of the 1, 3, and 5 years survival rates, major complication rates and local recurrence rates were performed. Data not amenable to pooling is presented in a qualitative and tabular manner. Thirty radiofrequency ablation (RFA), 11 cryoablation (CA), and 5 microwave ablation (MWA) studies were finally included in the qualitative synthesis. The number of patients included from all the studies was 3,107 patients; 2,021 in the RFA group, 988 in the CA, and 98 in the MWA. The forest plots confirm the significant heterogeneity of the included studies. Visual assessment of forest plots, as well as qualitative analysis of included papers suggested that between-studies heterogeneity was too great and thus, pooling through meta-analysis was not appropriate. RFA is the most commonly used ablative modality to treat unresectable CRCLM. Significant heterogeneity of the included studies was encountered precluding a meaningful meta-analysis. Future comparisons of local ablative therapies outcome necessitate prospective, randomized controlled studies.