Previous autoantibody (AAb) studies in multiple sclerosis MS have produced conflicting results. The objective of this study was to determine AAb frequency and association with the HLA-DRB1 genotype. Antinuclear antibody, antithyroid peroxidase and anti-aquaporin-4 assays and HLA-DRB1 genotyping were performed in 198 MS patients and 188 controls. There were no significant differences in AAb frequency or titres between MS and control subjects. AQP4-IgG was not found in any MS patients. There was no correlation between AAbs and HLA-DRB1 alleles. In conclusion, this study failed to confirm previous reports of increased AAbs in MS or to show an association between HLA-DRB1 genotype and the presence of AAbs.