Background <p>Multiple Sclerosis (MS) is a chronic demyelinating disease of the central nervous system with a growing prevalence. While various disease-modifying treatments (DMTs) are available, adherence to DMTs has remained a challenge in the management of MS. Among the previously known factors associated with adherence to DMTs, health literacy as an essential factor in health-related behaviors and a contributor to treatment adherence in other chronic diseases, has not been studied. This study aims to determine the role of health literacy in medication adherence among people living with MS.</p> Methods <p>The current study is a multicenter cross-sectional study conducted in two centers affiliated with the Isfahan University of Medical Sciences. A total of 317 participants were recruited using random systematic sampling. The participants were assessed for eligibility via the phone call. Data was then collected via a form for demographic and disease-related information, a revised version of the Multiple Sclerosis Treatment Adherence Questionnaire (rMS-TAQ), and the Health Literacy Questionnaire for Multiple Sclerosis patients (MSHLQ). Statistical analysis included descriptive statistics, Spearman’s correlation, and stepwise linear regression. Data analysis was carried out by IBM SPSS Statistics version 24.</p> Results <p>76.3% of participants were adherent (doses missed = 0). The health literacy score in MSHLQ was moderately associated with medication adherence score in rMS-TAQ (Spearman’s rho = 0.553, <i>p</i> &lt; 0.001). A final regression model was found significant (F(3, 316) = 43.877, <i>p</i> &lt; 0.001), which predicted adherence score in rMS-TAQ based on total health literacy score, the score in the ‘knowledge of caring for the disease’ subscale of MSHLQ, and income.</p> Conclusion <p>Health literacy is associated with better adherence to DMTs. Disease knowledge may play a mediating role in the relationship between health literacy and medication adherence in people living with MS.</p>