Introduction: In recent years, more and more attention has been given to the possibility of the co-occurrence of diseases grounded in autoimmune disorders. Recognizing the coexistence of two or a larger number of diseases, in the pathogenesis of which autoimmune disorders play a role, allows modification of treatment in order to achieve early improvement of the patient’s general condition. It is generally known that autoimmune disorders play a role in the pathogenesis of Crohn’s disease. What is more, it is also known that Hashimoto type thyroid gland inflammation and Graves-Basedow disease are the most frequent diseases with an autoimmune basis.

Aim: To analyse the condition of patients with Crohn’s disease from the point of view of chronic Hashimoto type thyroid gland inflammation co-occurrence.

Material and methods: In the research we examined a group of 58 patients (31 women and 27 men) with diagnosed Crohn’s disease in endoscopic and histopathological examination and a research sample (23 women and 22 men) with an affected abdominal cavity without any nonspecific inflammation diagnosed. All of the patients were over 16 years old and gave their consent for participation in the examination. The following examinations were made in the analysed groups: TSH, aTPO, aTG, TSHR.

Results: As a result of the analysis, a statistically significant increase of the frequency of thyroid gland function disorders in patients with Crohn’s disease was found.

Conclusions: Therefore, it seems to be advisable to consider the implementation of diagnostics for thyroid gland diseases in patients with diagnosed Crohn’s disease and the treatment of a possible coexisting disease of the thyroid gland may accelerate the acquisition and maintenance of long-term remission of the essential disease.