Objective: In this study our main goal is to evaluate the frequency of thyroid dysfunction and abnormal uterine bleeding. Method: This cross-sectional study was carried out at North East Medical College and Hospital, Sylhet from January 2019 to August 2019. A convenient sample of 40 women with AUB was selected after eligibility to inclusion and exclusion criteria. Another sample of 40women with normal cycle selected as control cases. Results: During the study, comparing AUB women with control women with no AUB revealed no significant differences regarding occupation (p=0.9), marital status (p=0.2), parity (p=0.3), BMI (p=0.3), and euthyroid women wile on thyroid replacement therapy (p=1.0). There was a significant association between positive contraception history and women with AUB (p=0.001). No significant differences were observed between AUB women and controls regarding post coital bleeding (p=0.1) and history of Pap smear (p=0.07). There was a significant association between intermenstrual bleeding and women with AUB (p=0.02). The common interesting findings in our study were the significant association between high TSH level and women with AUB (p=0.002). No significant differences were observed between AUB women and controls regarding T3 level (p=0.5). Women with AUB were significantly associated with low T4 level (p=0.04); 10% of AUB women had low T4 level. a significant association was observed between women with AUB and hypothyroidism (p=0.003); 22% of AUB women had hypothyroidism while 2% of controls had hypothyroidism. Conclusion: A significant cause of thyroid dysfunction is abnormal uterine bleeding in women of reproductive age. Thyroid hormones should be taken into account in the evaluation of patients with unexplained uterine bleeding.