The radiation segmentectomy technique may be defined as the administration of transarterial radioembolization delivered to 1 or 2 hepatic segments with the intention of segmental tissue ablation. Since first being described in 2011, radiation segmentectomy has quickly gained acceptance as a safe, effective, and potentially curative outpatient treatment for selected lower stage hepatocellular carcinomas. We describe our recommended techniques for radiation segmentectomy with glass or resin radiomicrospheres, including patient selection, dosimetry, microcatheter techniques, and clinical and imaging follow-up, accompanied by a brief review of the radiation segmentectomy literature. Radiation lobectomy, defined as the ablation of an entire hepatic lobe via transarterial radioembolization, is an area of growing interest in many centers. We also review the existing radiation lobectomy literature and suggest which patient and tumor factors may be associated with higher likelihood of successful treatment.