Background Long-term medication adherence is problematic among patients with chronic medical conditions. To our knowledge, this was the first study to examine factors associated with nonadherence among patients with relapsing-remitting multiple sclerosis who discontinue disease-modifying treatments against medical advice. Purpose To examine differences in perceived provider autonomy support between disease-modifying treatment-adherent relapsing-remitting multiple sclerosis patients and relapsing-remitting multiple sclerosis patients who discontinued disease-modifying treatments against medical advice. Methods Self-report questionnaires and a neurologic exam were administered to demographically matched adherent (n = 50) and nonadherent (n = 79) relapsing- remitting multiple sclerosis patients from the Midwest and Northeast USA. Results Adherent patients reported greater perceived autonomy support from their treatment providers, F(1, 124) = 28.170, p < .001, partial eta(2) = .185. This difference persisted after controlling for current multiple sclerosis healthcare provider, education, disease duration, Expanded Disability Status Scale, perceived barriers to adherence, and prevalence of side effects, F(1, 121) = 9.61, p = .002, partial eta(2) = .074. Neither depressive symptoms, F(1, 124) = 1.001, p > .05, partial eta(2) = .009, nor the occurrence of a major depressive episode, chi(2)(1, N = 129) = .288, p > .05, differed between adherent and nonadherent patients. Conclusions Greater perceived autonomy support from treatment providers may increase adherence to disease-modifying treatments among patients who discontinue treatment against medical advice. Results may inform interventions for patients who discontinue treatment against medical advice. Relapsing-remitting multiple sclerosis patients who discontinue disease modifying treatments against medical advice report less perceived support from their physicians than patients who adhere to treatment.