Objective: To describe the course of disability in patients with benign multiple sclerosis-i.e., with an expanded disability status scale score < 3 10 years after disease onset-for up to 30 years after disease onset. We evaluated the proportion of patients remaining in the benign state on the long term and the factor associated with this favorable outcome and determined the pattern of disability course after the loss of the benign status. Methods: Patients were selected from the ReLSEP, a French population-based registry. We studied the probability (Kaplan-Meier method) and predictors (multivariate Cox model) of remaining < 3 after year 10, and the course of disability after score 3 according to the duration of the benign phase in patients with ≥ 30 years of follow-up (graphs of the course of the mean expanded disability status scale scores in subgroups of patients). Results: 2295/3440 patients had benign multiple sclerosis (66.7%). The probability of remaining benign at year 30 was 0.26 (95% CI 0.26-0.32). A young age at disease onset and a good recovery after the first relapse were associated with remaining benign. Graphs illustrate that those who lost their benign status between years 10 and 30 follow a two-stage course. Beyond score 3, disability accumulation is similar in all but lower disability scores at advanced age are associated with longer benign periods. Conclusion: The longer a patient remains in the benign state, the lower the final EDSS at advanced age.