Poly cystic Ovarian Syndrome (PCOS) is an endocrine disorder of reproductive age defined by the presence of any two out of three criteria: oligo and/or anovulation, excess androgen activity and/or polycystic ovarian morphology on ultrasound. Considering role of vitamin D (VD) (3, 4) and high prevalence (58%) of deficiency in PCOS of Pakistan. Researchers hypothesized that its correction would improve response to standard PCOS treatment. The objective is to compare PCOS parameters in intervention group (Group A) receiving VD supplementation and then PCOS care with control group (Group B) receiving standard PCOS care and then VD supplementation. A randomized open label trial: delayed-start design will be conducted on VD deficient PCOS females VD \< 20ng/ml ; Group A will receive VD injections 600,000 I.U I/M once with 1 gram calcium supplement daily in the initial 12 weeks. After that standard PCOS care; i) Glucophage XR 750 mg (once for 15 days then twice daily) ii) progesterone supplementation (1 capsule Progeffik 100 mg every 3 weeks, then 1 week off) and iii) calcium supplements will be given for next 12 weeks. PCOS females in Group B will receive standard PCOS care (same) with addition of VD and calcium supplementation after 12 weeks till study end point. Study outcomes will be comparison of i) hyperandrogenism by Free Androgen Index \[Total Testosterone, Steroid Hormone Binding Globulin ii) insulin Resistance by HOMA-IR (serum Insulin, Fasting Blood Glucose) and iii) oxidative stress by Total Antioxidant Capacity after 24-weeks in these Groups'd levels after supplementation will be assessed for confirmation of correction and calcium and albumin levels for detection of hypercalcemia. Results of this study will inform the clinicians to add VD before or after the standard PCOS care for rectification of endocrine and metabolic derangements as a cost-effective treatment and prevention strategy in these females.