Abstract Background Euthyroid sick syndrome (also known as non-thyroidal illness syndrome) can be described as abnormal findings on thyroid function tests that occur in the setting of a non-thyroidal illness (NTI), without preexisting hypothalamic-pituitary and thyroid gland dysfunction. After recovery from an NTI, these thyroid function test result abnormalities should be completely reversible, study of euthyroid sick syndrome in burn patients. Aim of the Work The aim of study is to examine the ability of Euthyroid sick syndrome in predicting prognosis in severe burn patients. Patients and Methods A case control study was conducted in burn ICU in Ain Shams University Hospitals from march 2022 to September 2022,88 patients were admitted to study with 44 burn case with ESS and 44 burn case without ESS according to inclusion and exclusion criteria. Results The results showed that the group with ESS are more associated with higher rate of morality, hospital stay and more poor prognosis with worse APACHE score levels compared to the burn group with ESS. The study showed that using APACHE score with T3 levels measurements are more accurate in detecting morality in burn ICU patient. Conclusion The study demonstrated that ESS are more associated with higher rate of morality, hospital stay and more poor prognosis with worse APACHE score levels.