Background: Selenium is an essential trace mineral that supports many body processes. It can help improve cognition, immune system function, and fertility and plays a key role in maintaining thyroid hormone metabolism and DNA synthesis and protecting the body from oxidative damage and infection.



Objective: to detect selenium level in a sample of thyrotoxic Egyptian patients and to detect whether it's level is affected in thyrotoxic Egyption patients with and without thyroid eye disease.



Patients and Methods: This prospective case-controlled-hospital-based study was carried out in out patient clinic of internal medicine department faculty of medicine Minia university from August 2021 to June 2022. the study included 50 subject divided into 2 groups :group1 which involved 35 Egtptian thyrotoxic patients (20 females and 15 males), group2 Consisted of 15 apparantly healthy subjects (10 females and 5 males) . patients were excluded if any of them were critically ill other thyroid diseases rather than thyrotoxicosis -any patient who was critically ill or recently admitted to ICU ,all included patients were subjected to history taking , clinical examination, laboratory investigation in the form of TSH,FT3,FT4,Selenium level and selenium by ELISA .





Results : the study domanastrated apredominant female gender and serum selenium level was significant low in this sample of thyrotoxic Egyptiian patients with and without eye disease as compared to control group.



Conclusion : Serum selenium levels was low in this sample of Egyptian thyrotoxic patients and may has a role in thyroid eye disease.

Key words: thyroid, eye disease, selenium .