Background: Polycystic ovary syndrome (PCOS) is a common hormonal disorder affecting women, often in their reproductive years. The present study was conducted to assess role of vitamin D supplementation among PCOS women with vitamin D deficiency. Materials & Methods: 100 women with PCOS with Vitamin D deficiency were divided into 2 groups of 50 each. Group I women were given Metformin &calcium 1000mg daily along with Vitamin D3 60K IU weekly for 6weeks followed by monthly for 4 months. Group II women were given Metformin 1000mg daily only. Assessment of serum total testosterone, serum fasting insulin for hyperandrogenism & IR was done. All were subjected to transabdominal ultrasound scan. Results: Age group 16-20 years had 8 patients in group I and 7 patients in group II, 21-25 years had 14 in group I and 19 in group I and, 26-30 years had 18 patients in group I and 14 patients in group II and 31-35 years had 10 in patients in group I and 8 patients in group II. The difference was non- significant (P>0.05). Vitamin D before treatment and after treatment in group I was 12.5 and 13.1 respectively and in group II was 13.2 and 13.7 respectively. The difference was significant (P< 0.05). In group I and II, mean BMI before treatment was 27.4Kg/m2 and 25.7 Kg/m2 and after treatment was 25.6 Kg/m2 and 24.8 Kg/m2 respectively. Waist hip ratio before treatment was 0.82 and 0.81 and after treatment was 0.80 and 0.78 respectively. Hirsutism before treatment was 13.4 and 13.56 and after treatment was 9.3 and 11.2 respectively. Ovarian volume before treatment was 8.6 cm3 and 8.7 cm3 and after treatment was 6.5 and 7.1 cm3 in group I and II respectively. The difference was non- significant (P> 0.05). Conclusion: Women deficient in vitamin D, should take calcium and vitamin D supplementation as it is safe and have few side effects.