en Endocrinology Endocrinology Original Research Original Research <strong>&nbsp;&nbsp;</strong><strong>&nbsp; Background: </strong>Vitamin D deficiency is related to rickets in children, and it can increase the risk of osteoporosis in adulthood. The aim of our study was to estimate the prevalence of vitamin D deficiency among healthy Iranian children and adolescents. Vitamin D levels less than 20ng/ml and between 20 and 30ng/ml was considered as vitamin D deficiency and insufficiency, respectively.<br> <strong>&nbsp;&nbsp; Methods: </strong>Relevant observational studies evaluating the prevalence of vitamin D deficiency through 1 January 1990 to 28 Dec 2016, were searched in several electronic databases including Iran-Medex, Scientific Information Database (SID), Irandoc, PubMed and NLM Gateway (for MEDLINE), Web of Science, and Scopus with no restriction on language. Only full-text articles were used for data extraction and synthesis after considering the inclusion/exclusion criteria.<br> <strong>&nbsp;&nbsp; Results:</strong> 11 studies included; the data of four studies of Iranian newborns were withdrawn because of their high heterogeneity. The prevalence of vitamin D deficiency in Iranian boys and girls were 35% (CI 95% 34&ndash;37) and 61% (CI 95% 60&ndash;63), respectively. The prevalence of vitamin D insufficiency in Iranian children and adolescents was 31% (CI 95% 30&ndash;31).<br> <strong>&nbsp;&nbsp; Conclusion:</strong> It seems that the prevalence of vitamin D deficiency is very high among Iranian children and adolescents. The present findings could provide practical information for healthcare decision makers.<br> &nbsp;<br> &nbsp; Vitamin D deficiency, Insufficiency, Prevalence, Children, Iran 480 485 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1741-13&slc_lang=en&sid=1 Maryam Jazayeri maryamjazayeri@yahoo.com 200319475328460040211 200319475328460040211 No Department of Biochemistry, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Yousef Moradi Yousefmoradi211@yahoo.com 200319475328460040212 200319475328460040212 No Department of Epidemiology, School of Public Health, Iran University of Medical Science, Tehran, Iran Arezoo Rasti rastirf@yahoo.com 200319475328460040213 200319475328460040213 No Department of Basic Sciences, Medical-Surgical Nursing, School of Nursing and Mid-wifery, Tehran University of Medical Sciences, Tehran, Iran Manouchehr Nakhjavani nakhjavanim@tums.ac.ir 200319475328460040214 200319475328460040214 No Endocrinology and Metabolism Research Center, Vali-Asr Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mahboobeh Kamali kamali.m@iums.ac.ir 200319475328460040215 200319475328460040215 No Central library and Archive Center, Iran University of Medical Sciences, Tehran, Iran Hamid Reza Baradaran baradaran.hr@iums.ac.ir 200319475328460040216 200319475328460040216 Yes Endocrinology Research Center, Institute of Endocrinology and Metabolism, Iran University of Medical Sciences, Tehran, Iran & Ageing Clinical & Experimental Research Team, Institute of Applied Health Sciences, University of Aberdeen, Aberdeen, Scotland, UK