A new clinical guideline from the American Society for Radiation Oncology (ASTRO) provides guidance on the use of radiation therapy to treat adult patients with primary liver cancers using external beam radiation therapy (EBRT). Evidence-based recommendations outline indications and optimal EBRT dosing, techniques and treatment planning for patients with hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHC), with a strong emphasis on multidisciplinary care. The guideline, ASTRO’s first for primary liver cancers, is published in Practical Radiation Oncology.