Aim of the work: The aim of this work was to detect the relationship between Rheumatoid arthritis and thyroid dysfunction in the form of thyroid dysfunction and/or thyroid autoimmune disease. Patients and Methods: Eighty consecutive patients diagnosed with Rheumatoid arthritis (RA) according to the revised American College of Rheumatology criteria of 1988, attending the outpatient clinic of the Rheumatology and Rehabilitation Department were included in this study. All of them were subjected to detailed history taking, clinical examination and laboratory investigations, and plain X-rays of hands and feet. Eighty healthy age and sex matched participants were included in this study as well. Both groups were tested for thyroid profile, and tested for thyroid antibodies in the form of Antithyroid peroxidase (AntiTPO) and AntiThyroglobulin (AntiTG) antibodies. Results: Fifteen RA patients (18.75%) were found to have thyroid dysfunction, 4 of which were known to have subclinical hypothyroidism; 3 were regular on treatment and showed normal thyroid hormone levels; 1 patient was off treatment and showed laboratory evidence of thyroid dysfunction in the form of subclinical hypothyroidism. Five other patients showed subclinical hypothyroidism, but were not known to have thyroid dysfunction of any sort. Six patients of our study group showed elevated levels of thyroxine (FT4) with no corresponding suppressed/decreased thyroid stimulating hormone (TSH). Whereas among the control group 2/80 (2.5%) showed subclinical hypothyroidism, and 3/80 (3.75%) showed elevated FT4 levels, and statistical significance was only found as regards to subclinical hypothyroidism being higher among RA cases (p=0.009). AntiTPO was positive in 10/80 (12.5%) of cases and 9/80 (11.2%) of control group . Anti-TG was positive in 42/80 cases (52.5%), and 32/80 (40%) of control with a statistical significance (p value=0.003). Patients with thyroid dysfunction did not show statistical difference as regards to DAS, MHAQ, or modified Larsen's score as compared to those with normal thyroid profile. Conclusion: Subclinical Hypothyroidism was more common among RA cases when compared to controls. Furthermore had higher levels of AntiTPO and AntiTG when compared to RA cases with normal TSH levels. However, did not show higher levels of DAS,