Inclusion criteria:  Major subject (≥18 years old) Suffering from relapsing-remitting MS (RRMS) Supported in a neurology department at Strasbourg or Nancy University Hospital between 10/01/2018 and 11/31/2020. Treated with ocrelizumab 600mg every 6 months during the period from 01/10/2018 to 01/05/2020. Have had an M0, M3 / M6 and M12 MRI after initiation of treatment. Subject not having expressed his opposition, after information, to the reuse of his data for the purposes of this research  Exclusion criteria:  Subject having expressed opposition to participating in the study Primary progressive multiple sclerosis (MS-PP), secondarily progressive (MS-SP) Subject not meeting all the inclusion criteria Impossibility of providing the subject with enlightened information (difficulties in understanding the subject, etc.) Subjects under safeguard of justice Subject under guardianship or guardianship