An isolated CNS relapse is rarely seen in acute myeloid leukemia. However, it has a potentially fatal clinical outcome. We herein present the case of a 39-year-old man, who presented to our emergency room with horizontal diplopic images, vertigo, bilateral deafness, and progressing somnolence. Cerebral imaging revealed cerebral and cerebellar edema and a diffuse leukoencephalopathy. With the one-year-old history of an initially successfully treated FAB-M0 acute myeloid leukemia (AML) in mind, a lumbar puncture was carried out that showed a vast number of myeloid blasts in the morphologic analysis of the cerebrospinal fluid. In conjunction with normal findings in the peripheral blood-count with differential and the bone marrow examination a diagnosis of an isolated CNS relapse of the AML was made. Cytarabine chemotherapy was initiated and the symptoms resolved rapidly. To our surprise, cerebral imaging in the course of the treatment not only showed a resolution of the brain edema but also of the leukoencephalopathy, pointing to a direct infiltration of brain parenchyma by leukemic blasts. The case highlights the relevance of the CNS as a pharmacologic "sanctuary" for tumor cells in patients that on prior treatments have not received intrathecal chemotherapy or chemotherapeutics that cross the blood-brain barrier.