The primary purpose of this article is to document whether demographic, clinical, regimen-related, intrapersonal, and interpersonal factors predict medication non-adherence for vasculitis patients. A secondary purpose is to explore whether adherence varies by medication type and whether patients experienced drug-related side effects. Vasculitis patients (n = 228) completed online baseline and 3-month follow-up surveys. Demographic (age, gender, education, race, marital status, and insurance status), clinical (perceived vasculitis severity, disease duration, vasculitis type, and relapse/remission status), regimen-related (experience of side effects), intrapersonal (depressive symptoms), and interpersonal (adherence-related support from family and friends) factors were measured at baseline. Medication non-adherence was assessed at follow-up using the Vasculitis Self-Management Survey medication adherence subscale (α = 0.89). Variables that significantly correlated (p < 0.05) with non-adherence were included in a linear regression model to predict non-adherence. Younger age (r = -0.23, p < 0.001), female sex (r = 0.16, p < 0.05), experience of side effects (r = 0.15, p < 0.05), and more depressive symptoms (r = 0.22, p < 0.001) were associated with more medication non-adherence. In the regression model, younger age (β = -0.01, p = 0.01) and more depressive symptoms (β = 0.01 p = 0.02) predicted worse adherence. For six out of eight vasculitis medication types, patients who experienced side effects were less adherent than patients who did not experience side effects. Multiple factors are associated with medication non-adherence for vasculitis patients. Providers should discuss medication adherence and drug-related side effects with vasculitis patients. Providers may want to particularly target younger patients and patients with clinical signs of depression.