This article reviews the therapeutic efficacy and complications of microwave ablation (MWA) in the treatment of primary and secondary liver malignancies. A PubMed search using keywords 'microwave', 'liver', 'malignancy', 'cancer' and 'tumour' was performed to identify articles related to MWA of liver malignancies published in English from 1975 to February 2008. MWA is an effective treatment options for both primary and secondary liver malignancies with survivals comparable with those of liver resections. Local recurrences can be managed with further ablation. Small tumour size, well-differentiated tumour and a reduced number of lesions are factors associated with good prognosis. Temporary occlusion of the portal venous and hepatic arterial flow may increase the size of ablation but the safety aspect requires further validation. MWA is a minimally invasive technique that has broadened the therapeutic option for patients with conventionally unresectable liver tumours with promising survival data. Future advances in the applicator design and treatment monitoring may further improve its efficacy and widen the indications.