US residents can face serious financial barriers to obtaining prescription medications, including disease-modifying medications for multiple sclerosis (MS). We conducted 30-min telephone surveys with 983 persons with MS nationwide, 21-64 years old, to explore how financial and health insurance concerns affect access to services including MS drugs. Almost everyone (96.3%) had some health insurance. Multivariable logistic regression analyses accounted for demographic, disease and insurance characteristics. Only 10.8% of those <40 years old had never received disease-modifying medications, compared with 41.1% of persons aged 60-64. Among the uninsured, 36.8% reported having never taken these medications, compared with 21.2% of persons with health insurance. Adjusted odds ratio (95% CI) of using these drugs in prior 12 months among the uninsured (compared with insured persons) was 0.28 (0.08, 0.95). Just over 16% of persons with public health plans reported that their insurer initially denied coverage for MS medication. When asked about MS medications in general, 22.3% reported having not filled prescriptions, skipping doses or splitting pills because of cost concerns; 22.4% worried ;a lot' about getting MS medications when they needed them. Substantial fractions of persons with MS confront financial and health plan-related barriers to obtaining MS drugs.