Objective: Several immunological factors are emphasized in the etiology of autoimmune thyroid diseases and obsessivecompulsive disorder. Obsessive-compulsive symptoms (OCS) are commonly seen in patients with autoimmune thyroid diseases. This study aims to evaluate the relationship between OCS and antithyroid antibodies. Methods: The study included 145 patients with Hashimoto thyroiditis or Graves’ disease and 42 healthy controls. Thyroid function tests and serum thyroid autobody levels (anti-thyroglobulin [TG], anti-thyroid peroxidase [TPO], and anti-thyroid stimulating hormone [TSH]) of the patients were measured. The socio-demographic data and OCS of the participants were evaluated with Dimensional OCS (DOCS). Results: DOCS scores were higher in patients than in the control group. There was not found a significant relationship between free T3, free T4, and TSH levels and DOCS scores. Anti-TG positivity in females was associated with lower DOCS scores. Anti-TPO positivity in males had a positive correlation with DOCS scores. There was no correlation between sex and the presence of anti-TSH in terms of OCS severity. Univariate analysis found the highest OCS scores in anti-TPO positive, anti-TG, and anti-TSH negative patients. The group with the lowest OCS scores was found to be anti-TG positive, anti-TPO, and anti-TSH negative patients. Conclusion OCS severity could be affected by different thyroid autoantibody profiles in patients with autoimmune thyroid diseases. While anti-TG serves a protective role against OCS in females, the presence of anti-TPO may worsen the OCS in men. Additionally, the co-existence of different antithyroid antibodies may affect the severity of OCS differently according to sex.