The paper has reviewed the use of Selective Internal Radiation Therapy (SIRT) using SIR-Spheres, which is a therapeutic ÂÂdeviceÂÂ for the treatment of non-resectable hepatic metastases secondary to colorectal cancer in the absence of extrahepatic metastases. SIRT involves a single delivery of Yttrium 90micro-spheres in the hepatic artery. Preferential uptake is achieved into liver tumors, because of their predominant hepatic arterial blood supply. The treatment is well tolerated and has been documented internationally to achieve response rates of around 90% in patients with extensive colorectal cancer (CRC) liver metastases. The product obtained FDA approval in the USA in 2002. Unlike other ablative therapies being applied to non-resectable liver tumors, SIRT is indicated even in patients with an extensive burden of liver tumor. Indications, dosing schedules and expected outcomes will be better defined.