Background: The precise relationship between polycystic ovarian syndrome (PCOS) and thyroid gland function is still unknown. However, both conditions share a variety of symptoms, including obesity, menstrual irregularities, hirsutism, infertility, and insulin resistance. Objectives: To find out the prevalence and the possible link between hypothyroidism and PCOS. Patients and methods: Our study was conducted on 200 women for the presence or absence of PCO and hypothyroidism. Hormonal assay: (FSH, LH, TSH, FT3, FT4, testosterone) as well as fasting plasma glucose, HbA1c, TPO ab and thyroglobulin ab, HOMA – IR, Neck US, Pelvic-abdominal US were performed to all patients. Results: Overt hypothyroid patients in PCOS group demonstrated significantly higher PCOS criteria, infertility than those with no hypothyroidism. PCOS patients in hypothyroid group had significantly higher testosterone (0.63 ±0.14 vs 0.39 ±0.05 ng/dl), TPO antibody (median = 489 vs 203 IU/ML), and TG antibody (362.5 vs. 98 IU/ML) than patients without PCOS. Our results revealed that insulin resistance is a common finding in both condition that is inferred from the following: Patients with hypothyroidism in PCOS group demonstrated significantly higher weight (94.6 ±22.8 vs. 80.3 ±20.5 kg), BMI (34.7 ±8 vs. 30.5 ±7.5), and waist circumference (101 ±15 vs. 94 ±15 cm). Meanwhile, in hypothyroidism group, PCOS patients had higher fasting plasma glucose (127 ±30 vs 88 ±17), HBA1C (6.32% ±0.95 vs 5.07% ±0.59), HOMA-IR (median = 3.05 vs 0.9). Conclusion: There is an association between PCOS and hypothyroidism per se, neither related to the underlying etiology nor to clinical presentation.