A 66-year-old man with colorectal carcinoma and liver-only metastases underwent radioembolization using Y-loaded, resin-based microspheres. One day after radioembolization, the patient experienced severe hypertension and multiple seizures. On MRI, symmetric edematous areas in the cerebellum and the parietal and occipital lobe were observed, a typical finding for posterior reversible encephalopathy syndrome (PRES). The PRES is associated with, for example, renal failure or blood pressure fluctuations leading to cerebral endothelial dysfunction. Antihypertensive and antiepileptic therapies led to normotensive blood pressure and neurological remission. Therefore, newly developed neurological symptoms accompanied by high blood pressure fluctuations after radioembolization should lead to PRES as differential diagnosis.