Intravascular malignant lymphocytosis (IML) is a rare systemic disease characterized by proliferation of malignant B (rarely T) lymphoid cells within the lumina of small arteries, veins, and capillaries. Diagnosis requires skin, liver, renal, meningeal, or brain biopsy, but is rarely made ante mortem. In this report, we describe a patient who had an ante mortem diagnosis of IML as a result of a skin biopsy. Autologous peripheral blood stem cell transplantation (auto-PBSCT) was successfully performed after chemotherapy. The patient has survived for more than 30 months since the onset of the disease and maintains complete remission on the 450th day post PBSCT. To our knowledge, this is the first case of IML treated by auto-PBSCT.