Abstract Introduction Limited data exist with respect to the outcome and optimal management of patients with myelomatous involvement of their central nervous system (CNS). Methods Of 4060 patients with multiple myeloma (MM), evaluated at Mayo Clinic MN between 1998 and 2014, 29 patients (0.7%) had identifiable CNS involvement, established by the presence of atypical plasma cells in the cerebrospinal fluid (CSF) and/or identification of intraparenchymal/meningeal involvement on magnetic resonance imaging (MRI). A cohort of 87 MM patients without CNS disease served as a control group (1:3), matched by diagnosis date and gender. Results Plasma cells were detected in the CSF in 87% and MRI findings consistent with CNS involvement were noted in 82% of the patients. Bone marrow plasma-cell labeling index ≥ 3%, presence of disease at other extramedullary sites or peripheral-blood plasma cells > 800 per 150,000 events were associated with an odds ratio of 7.1, 10.3 and 14, respectively for the risk of CNS involvement. Overall survival (OS) from diagnosis of MM was significantly shorter in the CNS-MM group (median 40 months, 95% CI:24-56) compared to the control group (median 93 months, 95% CI:67-129). OS was 3.4 months from the time of detection of the CNS disease. Patients who underwent autologous stem-cell transplantation post CNS involvement (n=7) had a median OS of 19 months (95%CI:10-67) from the time of CNS involvement. Conclusion Myelomatous involvement of the CNS is a rare complication that portends poor survival. Current therapeutic approaches appear to be largely ineffective in this subset of myeloma patients.