A 47-year-old woman was admitted to our hospital complaining of persistent fever and dry cough in June 2007. CT scan showed hepatosplenomegaly. Laboratory data revealed pancytopenia and increased levels of LDH and soluble interleukin-2 receptor. Malignant lymphoma was suspected, but histological diagnosis was difficult because superficial lymph nodes could not be palpated. Histological examination of the bone marrow biopsy specimen demonstrated the proliferation of large atypical lymphoid cells positive for CD20 and CD79a in the small capillaries, leading to the diagnosis of intravascular large B-cell lymphoma (IVLBCL). Although the results of neurological examination and CSF analysis were normal, head MRI showed a T2-hyperintense lesion in the pons. We chose R-hyper-CVAD/R-MTX-Ara-C alternating therapy with MTX intrathecal injection because CNS involvement in IVLBCL was highly suspected, and she responded well. Head MRI showed the disappearance of the abnormal signal in the pons after one cycle of R-hyper-CVAD. Five cycles of R-hyper-CVAD/R-MTX-Ara-C were performed and complete remission was obtained. R-hyper-CVAD/R-MTX-Ara-C alternating therapy was effective in an IVLBCL patient with CNS involvement.