Introduction: Coronavirus disease 2019 (COVID-19) is the biggest health challenge of recent times. Studies so far reveal that vaccination is the only way to prevent this pandemic. There may be factors that decrease or increase vaccine effectiveness. In multiple sclerosis (MS), some of these factors may cause changes in the effectiveness of the vaccine, depending on the nature of the disease and disease-modifying treatments (DMT). In this study, we aimed to investigate the relationship between antibody titer and smoking in non-treated and DMT-treated MS patients who received inactivated vaccine (Sinovac) and messenger RNA BNT162b2 (BioNTech) mRNA vaccines. Method: Vaccine antibody responses were measured between 4–12 weeks after two doses of inactivated vaccine and mRNA vaccines. Patients were separated into 6 groups as: patients with MS without treatment PwMS w/o T, ocrelizumab, fingolimod, interferons (interferon beta-1a and interferon beta-1b), dimethyl fumarate, and teriflunomide. Antibody titers of smokers and non-smokers were compared for both vaccines and for each group. Results: The study included 798 patients. In the mRNA vaccine group, smokers (n=148; 2982±326 AU/mL) had lower antibody titers compared to the non-smokers (n=244; 5903±545 AU/mL) in total (p=0.020). In the inactivated vaccine group, no significant difference was detected between smokers (n=136; 383±51 AU/mL) and non-smokers (n=270; 388±49 AU/mL) in total (p=0.149). In both vaccine groups, patients receiving ocrelizumab and fingolimod had lower antibody titers than those receiving other DMTs or PwMS w/o T. In untreated MS patients, antibody levels in smokers were lower than in non-smokers in the mRNA vaccine group. No difference was found between antibody levels of smokers and non-smokers in any of the inactivated vaccine groups. Conclusion: Ocrelizumab and fingolimod have lower antibody levels than PwMS w/o T or other DMTs in both mRNA and inactivated vaccine groups. Smoking decreases antibody levels in the mRNA vaccine group, while it has no effect in the inactivated vaccine group.