Rituximab has demonstrated a major effect in B-cell lymphoma and in a wide range of autoimmune disorders. Unfortunately, the blood-brain-barrier excludes the disorders restricted to the central nervous system (CNS) from the action of rituximab. The progressive phase of multiple sclerosis (MS) is a prototypical CNS autoimmune disorder characterized by an intrathecal compartmentalization of inflammation resisting all the available immunosuppressive treatments. As a consequence, intrathecal therapeutics are promising new approach in progressive MS. We first review data gathered from animal models and human off-label intrathecal rituximab use in CNS lymphomas, then summarize the recent evidence supporting the need for trials based on the intrathecal use of rituximab in multiple sclerosis. The experience obtained in these settings offers valuable preliminary data for future studies in CNS autoimmunity.