There have been few reports on central nervous system (CNS) involvement in chronic lymphocytic leukemia (CLL). This is an extremely rare disease with poor prognosis, owing to resistance to various treatments. We describe a 33-year-old man with intractable CLL with CNS involvement. He was diagnosed with CLL, with diplopia as the first manifestation. Magnetic resonance imaging revealed a contrast-enhancing tumor in the right temporal lobe, which was diagnosed as CNS involvement in CLL on brain biopsy. High-dose methotrexate therapy was ineffective for this lesion, which was also resistant to subsequent whole-brain irradiation, treatment with fludarabine-cyclophosphamide-rituximab chemoimmunotherapy, and ibrutinib administration. Because no standard protocol exists for CLL with CNS involvement, it is important to accumulate case data to verify the choice of new drugs for administration at an early stage. Therefore, we also conducted a literature review of 50 case reports of CNS lesions in the last 10 years to consider the pathophysiology, diagnosis, and treatment of CNS involvement in CLL. The possibility of new therapeutic agents, eg, ibrutinib and venetoclax, or a combination of these agents and methotrexate, can be envisioned as a treatment strategy for CLL with CNS involvement.