On the basis of various clinical and MRI measurements, the phase 3 Cladribine Tablets Treating Multiple Sclerosis Orally (CLARITY) study in patients with relapsing-remitting multiple sclerosis (RRMS) showed that short-course oral treatment with cladribine at cumulative doses of 3·5 and 5·25 mg/kg over 96 weeks was more effective than placebo. Achieving sustained freedom from disease activity is becoming a viable treatment goal in RRMS; we therefore aimed to assess the effects of cladribine on this composite outcome measure by doing a post-hoc analysis of data from the CLARITY study.