Background: Polycystic ovary syndrome had unclear etiology, affecting 6-12% of females due to undetermined optimal treatment.

Studies indulge vitamin D in pathogenesis of PCOS but without evidence demonstrating its effect on PCOS.

Aim of the Study: Our objective is evaluation of vitamin D supplementation on ovulation in sub-fertile females with PCOS.

Patients and Methods:
Two hundred cases of PCOS at Al-Azhar University Hospital and Damanhour teaching Hospital were selected based on clinical diagnosis, ultrasonographic and laboratory findings. They were 100 cases of PCOS managed by clomifine citrate plus vitamin D and another 100 cases managed only by clomifine citrate.

Results:
Our results didn't show a difference between both groups regarding demographic data, hormonal profile, fasting sugar level of both cases and controls and also, radiological findings between both groups.

There was estradiol rise in serum level at time ovulation of cases; and increase pregnancy rate after induction but in doesn't reach a significant level without difference between both groups regarding complications after therapy.

Conclusion:
We can concluded that addition of vitamin D to clomifine is beneficial in increasing pregnancy rate even with a non-significant effect and so, we recommend its addition to the protocol of management in cases of PCOS.