Using placebo data from 3 randomized multiple sclerosis (MS) trials with uniform inclusion criteria, we investigated heterogeneity of Expanded Disability Status Scale (EDSS) progression by geographical areas. Our analysis revealed a significantly lower EDSS progression in Eastern European countries (10.8%) compared with Western Europe (13.1%) or the USA/Canada (21.4%, p < 0.001); EDSS improvement behaved the same way. This heterogeneity is not explained by differences of baseline variables. No differences were detected on more easily quantifiable measures, the Timed 25‐Foot Walk or the Multiple Sclerosis Functional Composite. At a time when disease progression represents the target for future interventions in MS, establishment of more quantitative and objective outcomes remains a key priority of MS research. Ann Neurol 2018;84:621–625