Background: Abnormal uterine bleeding (AUB) is a term used to describe any type of bleeding that does not fall within the normal range of amount, frequency, duration and cyclicity. The prevalence is 9-14% of women from menarche to menopause and also affects the quality oflife.1 ApproximatelylS-26% of menstrual disorders are attributed to thyroid dysfunction.2 Objective: To categorise the patients into four categories- euthyroid, subclinical hypothyroid, hypothyroid, hyperthyroid and determine the type of menstrual bleeding pattern in relation to different thyroid disorders. Materials and Methods: We did a prospective observational (non-interventional) study at Department of Obstetrics and Gynaecology, Kamala Nehru Memorial Hospital, Prayagraj from July 2019 to June 2020. A total of 100 patients attending the inpatient and outpatient of the department in the age group of 15-45 years with complaints of menorrhagia, oligomenorrhoea, polymenorrhoea, amenorrhoea and hypo menorrhoea fulfilling the inclusion criteria and exclusion criteria were included in the study. The patients were categorized into four groups: euthyroid, hypothyroid, subclinical hypothyroid and hyperthyroid, and then comparison among all the groups were done with respect to age, parity, BMI, TSH, FT31 FT4 levels and histopathological findings. Results: All the groups were comparable in terms of age, parity, BM I and family history although the majority of cases of AU B was found in the age group of 36-45 years. Subclinical hypothyroidism was found to be the most prevalent thyroid disorder with menorrhagia as the most common menstrual disorder. Hyperthyroid patients had oligomenorrhoea as the most common complaint. This association was not found to be statistically significant (p>0.05). Proliferative endometrium was found to be more commonly associated with euthyroidism and hypothyroidism (subclinical and overt) while secretory endometrium was seen in hyperthyroidism. This association was not found to be statistically significant (p>0.05). Conclusion: The present study reported high incidence of thyroid diseases in patients of AU B. Thyroid function evaluation she u Id be mandatory in cases of AUB to detect thyroid dysfunction and these cases should be referred to physician for further medical treatment. [ABSTRACT FROM AUTHOR]