Background and Aim: In most cases the vitamin D₃ through food sources is not sufficient, the same food sources are limited and cannot meet the needs of children and adults. Due to lack of studies in the field of D₃ vitamins, especially in Tehran, as well deficiency of this vitamin, we decided to determine deficiency rate of this vitamin in north of Tehran city.

Materials and Methods: This cross-over study was performed in during January 2013 to January 2016 on 873 patients between the all ages in north of Tehran. Vitamin 3D measuring performed by ELecsys 2010 apparatus.

Results: The results show that 63 % of surveyed peoples had insufficient level of vitamin D₃, of which approximately 21% suffer extreme poverty.

Conclusion: Vitamin D₃ deficiency observed in north of Tehran city and is in a critical condition. Therefore, proper notification by hospitals, laboratories and other medical centers is necessary.