Radiofrequency ablation (RFA) of liver tumors has quickly gained acceptance since its introduction in the early 1990s. This technique is increasingly being used to treat liver metastases from colorectal (CRC) cancers. Most of the published trials of RFA in CRC patients are retrospective analyses; no prospective comparisons of RFA vs. resection or chemotherapy are yet available. Nevertheless, conclusions that can be safely drawn from available data include that RFA effectively destroys very small tumors, it is minimally invasive, is better able to spare uninvolved liver than is liver resection, and is associated with lower treatment costs than surgical resection. The major limitation of RFA is the high rate of local recurrence in treated patients. Potential contributors to the high local recurrence rate are discussed, including the current RFA technique, large blood vessels serving as "heat sinks," potential islands of viable tumor cells within an ablated zone, and the need for improved methods of real-time feedback. Improved multidisciplinary evaluation and treatment planning are needed for better management of patient candidates for RFA. Furthermore, prospective studies with defined end points and detailed documentation of the RFA technique are needed.