Three years after the introduction of natalizumab (NA) therapy for the second line treatment of relapsing-remitting multiple sclerosis (MS), Italian MS centers critically reviewed the scientific literature and their own clinical experience. Natalizumab was shown to be highly efficacious in the treatment of MS. However, the risk of progressive multifocal leukoencephalopathy was confirmed and defined better. This article summarizes the MS-SIN Study Group recommendations on the use of NA in MS, with particular reference to the appropriate selection and monitoring of patients as well as to the management of adverse events.