Hepatocellular carcinoma (HCC) constitutes a difficult health challenge because of its poor prognosis and limited treatment options. Most available therapies are used only for palliation. The use of yttrium-90 microspheres is a new intraarterial therapy consisting of beta-irradiating microspheres measuring 20-30 micro m in diameter that can be delivered directly to the tumors. (90)Y microspheres, which carry the radiation, are selectively taken up by the tumors, thus preserving normal liver. In several studies to date, (90)Y microspheres have proved to have a low toxicity profile and have generally been well tolerated by patients. Other than transient elevation in liver enzyme levels and mild fatigue and fever, no substantial treatment-related toxicities have been observed. Gastrointestinal toxicities occur in a limited number of cases and are preventable with proper knowledge of visceral arterial anatomy. The effect on survival is also promising, with median survival rates of 23 months (95% confidence interval = 14, 44) and 11 months (95% confidence interval = 6, 26) for patients with Okuda stage I and stage II disease, respectively. On the basis of these data, intraarterial delivery of (90)Y microspheres offers a new alternative in the treatment of unresectable HCC.