en Health Health Review Article Review Article <span style="font-size: 14px;"><span style="font-family: times new roman;"><span style="color: rgb(0, 0, 255);"><strong><em>Background:</em></strong></span> Polycystic ovary syndrome (PCOS) is the most popular endocrine disorder in reproductive age with unknown etiology and many comorbidities.<strong> </strong>This systematic review focused on the effectiveness of calcium and vitamin D (Ca/ Vit.D) supplementation on metabolic factors, menstrual cycles, and follicular responses in PCOS patients.<br> <span style="color: rgb(0, 0, 255);"><strong><em>Methods:</em></strong></span> Relevant studies were identified from the following electronic databases including Pub Med, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library, issue Oct. 2018, Evidence Based Medicine Reviews (EBMR), Google Scholar, EMBASE, as well as Farsi databases including Magiran and SID from 2000 to 2018. Out of 449 articles, six clinical trials met the inclusion criteria.<br> <span style="color: rgb(0, 0, 255);"><strong><em>Results:</em></strong></span> Out of six studies included in the study, only three studies had sufficient data for meta-analysis. Overall, studies showed that prescribing Ca/ Vit. D supplementation with metformin improved menstrual regularity and follicular maturation and significant decreases in serum insulin levels, homeostasis model of assessment-insulin resistance (HOMA-IR) and fasting blood sugar (FBS) and also significant rises on quantitative insulin sensitivity check index (QUICKI) at two studies. Hirsutism and level of testosterone decreased significantly after adding Ca/ Vit. D to metformin in two different studies. Based on two different trials, co-supplementation of Ca/ Vit. D had a significant impact to decrease serum triglycerides and VLDL-cholesterol levels as well as levels of cholesterol and LDL.<br> <span style="color: rgb(0, 0, 255);"><strong><em>Conclusion:</em></strong></span> It is possible that calcium and vitamin D supplementation improve menstrual disturbances and metabolic factors in PCOS in a long-term period, but further trials are still needed to confirm these findings.</span></span> Calcium and vitamin D, Polycystic ovary syndrome, Metabolic factors, Manstrual cycle. 359 369 http://caspjim.com/browse.php?a_code=A-10-1338-1&slc_lang=en&sid=1 Zahra Shojaeian shojaeianz931@mums.ac.ir 100319475328460018809 100319475328460018809 No Department of Midwifery, School of Nursing and Midwifery, Mashhad University of Medical Sciences, Mashhad, Iran Ramin Sadeghi sadeghir@mums.ac.ir 100319475328460018810 100319475328460018810 No Nuclear Medicine Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Robab Latifnejadroudsary latifnejadr@mums.ac.ir 100319475328460018811 100319475328460018811 Yes Nursing and Midwifery Care Research Centre, Mashhad University of Medical Sciences, Mashhad, Iran