BackgroundGrowing literature supports the hypothesis that personality influences health outcomes. Few studies have examined the association between personality traits and key clinical manifestations in persons with multiple sclerosis (pwMS). ObjectiveTo investigate whether personality traits are associated with physical function, cognition, and depression in persons with MS. MethodsIn this cross-sectional study, we analyzed data from two cohorts (UPMC, n = 365 and CUIMC, n = 129). Participants completed a personality scale (assessing neuroticism, extraversion, openness, agreeableness, and conscientiousness) and validated surveys measuring physical function, cognition, and depression. Stepwise linear regressions were used to evaluate associations between personality traits and outcome measures. ResultsConsistently across cohorts, higher extraversion was associated with better physical function, whereas higher neuroticism was associated with worse depression. In the first cohort, higher extraversion was associated with better cognition, while higher neuroticism was associated with greater risk for memory impairment in the second cohort. Relationships were independent of age and disease duration. ConclusionFindings suggest a potentially protective role of extraversion, and a harmful role of neuroticism, in MS-specific patient-reported clinical outcomes. Increased understanding of the interplay between personality and health outcomes may inform risk models for physical decline, cognitive impairment, and depression in pwMS.