OBJECTIVE: Since thyroid dysfunction is a common disorder and affecting all populations regardless of iodine status, a comprehensive evaluation of thyroid dysfunction in Bahrain is essential to draw a national strategy, increase public awareness, and recognize the role of ethnicity. METHODS: Following the approval of the Research Ethics Committee, the study was initiated by collecting laboratory and patient’s data that have performed thyroid function tests (TFTs) during January 2018 till January 2019 at the Royal Services of Bahrain Defense Force (BDF) Military Hospital. TFTs data for 19,736 subjects were collected and analyzed using SPSS. RESULTS: Based on the TFTs measurements and including treated euthyroid, 44.9% of subjects had thyroid dysfunction categorized as treated euthyroid (15.1%), hypothyroid (20%), hyperthyroid (3.3%), and subclinical hypothyroid (6.5%). Females having thyroid dysfunction were 2.9 times more than males, and the most female age group affected was 20-<40 years old (14.1%). Furthermore, the frequency and the levels of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb) were related to the TSH level above or below 10 µIU/l. The frequencies of TPOAb and TGAb were 79% and 61%, respectively, in the treated hypothyroid group that have TSH>10 µIU/l and were significantly higher than the counterpart groups of TSH between 4-10 µIU/l (44% and 40%, respectively) (p<0.001). Similarly, the mean values of TPOAb and TGAb were significantly different between TSH>10 µIU/l and the counterpart groups of TSH between 4-10 µIU/l (p<0.001). CONCLUSION: This study showed that hypothyroidism predominates in the Bahraini population, and most of the patients were females with an age group of 20-<40 years old. In addition, the thyroid dysfunctions were correlated with the high percentages of positive frequencies with TPOAb and TGAb, indicating the predomination of autoimmune thyroid diseases. Besides, the determination of risk factors in relation to hypothyroidism occurrence such as genetic predisposition and loci genetic variants is highly essential. Also, more national studies and public awareness are needed to reduce the potential illnesses of thyroid dysfunction.