To the Editor Hatcher et al1 reported that 5 of 46 patients with multiple sclerosis who discontinued fingolimod treatment experienced severe relapse 4 to 16 weeks after discontinuation. A discerning reader would ask whether the relapses occurred in the context of a treatment switch or a complete absence of treatment, with the former being of greater clinical significance because it suggests that the new treatment did not protect against the postulated effect of fingolimod withdrawal. Regrettably, the authors did not present the required information in their abstract, nor did they examine the question in their discussion or conclusions. From the case material, however, we learn that there was only 1 patient (case 4) who was actually well at the time of fingolimod discontinuation, who was switched to another treatment (dimethyl fumarate), but who nevertheless relapsed.