Background: Copeptin is a useful and practical surrogate marker for AVP in clinical settings since it is co-secreted in equimolar amounts with AVP, the stable and physiologically inactive C-terminal part of pro-vasopressin. The present study was conducted to assess serum copeptin as a biomarker of polycystic ovarian syndrome and its correlation with metabolic syndrome components. Materials & Methods: The present study was conducted at Department of Gynae Oncology, IGIMS, Patna, Bihar, India during January 2019 to December 2021. 50 patients of polycystic ovarian syndrome of both genderswere divided into two groups: Group I subjects with PCOS having metabolic syndrome, and group II subjects with PCOS but not having metabolic syndrome. Serum insulin, total cholesterol, high- density lipoprotein cholesterol (HDL-C), and triglycerides (TG), low- density lipoprotein cholesterol (LDL-C) and Homeostasis Model Assessment Insulin Resistance Index (HOMA-IR)were measured. Results: In group I and group II, the mean BMI (kg/m2) was 31.4 and 23.7, waist HIP ratio was 0.89 and 0.81, serum copeptin (ng/mL) was 7.5 and 8.4, SBP (mmHg) was 123.5 and 112.6, DBP (mmHg) was 84.5 and 74.2, fasting plasma glucose (mg/dL) was 95.4 and 91.3, fasting serum insulin (uIU/mL) was 24.6 and 91.0, HOMA- IR was 5.6 and 2.6, total cholesterol (mg/dL) was 192.6 and 170.5, triglycerides (TG) (mg/dL) was 165.2 and 122.8, HDL-cholesterol (mg/dL) was 44.7 and 53.1 and LDL-cholesterol (mg/dL) was 125.2 and 102.8 respectively. The difference was significant (P< 0.05). Serum copeptin levels showed a significant correlation with fasting serum insulin (p=0.006) and HOMA-IR (p=0.012). There was a significant negative moderate correlation between serum copeptin and serum insulin levels, and between serum copeptin and HOMA-IR. Conclusion: Copeptin measures in plasma have very low sensitivity, hence the serum copeptin cannot be utilized as an independent diagnostic for the diagnosis of metabolic syndrome in PCOS patients.