Background: Six monthly courses of mitoxantrone were approved in France in 2003 for patients with highly active multiple sclerosis (MS).Objective: To report the 10-year clinical follow-up and safety of mitoxantrone as an induction drug followed by maintenance therapy in patients with early highly active relapsing-remitting MS (RRMS) and an Expanded Disability Status Scale (EDSS) score<4, 12months prior to mitoxantrone initiation.Methods: In total, 100 consecutive patients with highly active RRMS from the Rennes EDMUS database received monthly mitoxantrone 20mg combined with methylprednisolone 1g for 3 (n=75) or 6months (n=25) followed by first-line disease-modifying drug (DMD). The 10-year clinical impact was studied through clinical activity, DMD exposure, and adverse events.Results: Twenty-four percent were relapse-free over 10years and the mean annual number of relapses was 0.2 at 10years. The mean EDSS score remained significantly improved for up to 10years, changing from 3.5 at mitoxantrone initiation to 2.7 at 10years. The probability of disability worsening and improvement from mitoxantrone initiation to 10years were respectively 27% and 58%, and 13% converted to secondary progressive MS. Patients only remained untreated or treated with a first-line maintenance DMD for 6.5years in average. In our cohort, mitoxantrone was generally safe. No leukemia was observed and six patients developed neoplasms, including 4 solid cancers.Conclusion: Monthly mitoxantrone for 3 or 6months, followed by maintenance first-line treatment, may be an attractive therapeutic option for patients with early highly active RRMS, particularly in low-income countries.