BACKGROUND Primary hypothyroidism is the decrease in production and secretion of thyroid hormones by the thyroid gland. This is characterised by slackening of metabolism and leading to multiple system impairment. The important aetiological factors for primary hypothyroidism are congenital, iodine deficiency, autoimmune thyroiditis and iatrogenic. [1] Ovarian cysts are a common cause for gynaecological surgeries. The aetiology [2] of ovarian cysts can vary greatly including benign or malignant tumours, endometriosis and inflammation, etc. However, some cysts are direct result of endocrine disorders and do not require surgery. Hypothyroidism may cause reproductive and endocrinological disorders as well. The aetiopathogenesis is complex. In 1960 Van Wyk and Grumbach first described the relation between ovarian cyst and hypothyroidism. They proposed that there was a hormonal overlap in the pituitary feedback mechanism. It is due to the fact that TSH, GH, FSH and LH are all glycoproteins with a common alpha chain and may thus cross react. High TSH could produce FSH and LH like activity leading to luteinised ovarian cyst. The TRH may also act on pituitary cells to stimulate gonadotropin release and hence FSH and LH. Other postulated mechanisms are increased ovarian sensitivity to gonadotropins, altered metabolism of oestrogen, hypothalamopituitary dysfunction and altered prolactin metabolism. AIMS To study the percentage of ovarian cyst among the diagnosed cases of primary hypothyroidism and then to find out the association between hypothyroidism and ovarian cyst. To study the relation between level of TSH and size of ovarian cyst. To study the percentage of ovarian cyst among patients with TSH <50 mIU/L between 50-100 and >100 mIU/L separately.