Background: Iron deficiency impairs the proliferation and function of T lymphocytes. This study was conducted to assess the relationship between serum iron with percentage of TCD4 and TCD8 lymphocytes in peripheral blood of female high school students in Hamadan. 
Methods: In this cross-sectional study, 355 female high school students with an age range of 15-18 years were enrolled from January 2016 to March 2017. After approval by the ethics committee of Hamadan University of Medical Sciences, taking written consent of parents, and completion of a questionnaire involving demographic information, serum iron profile, the percentage of TCD4 and TCD8 cells, and TCD4/TCD8 ratio were measured using standard methods. The results were analyzed by SPSS software, version 13. 
Results: The prevalence of iron deficiency anemia was 16.1% in 355 female high school students of Hamadan. There was no correlation between transferrin saturation with percentage of TCD4 lymphocytes and TCD4/TCD8 ratio in the two groups of students with and without iron deficiency (P>0.05). However, a significant correlation was found between Tfs with percentage of TCD8 lymphocytes in the group of patients with iron deficiency anemia (P<0.05).
Conclusion: This study indicated an increased percentage of TCD8 lymphocytes with reduced Tfs in patients with iron deficiency anemia. In addition to reduced Tfs, other factors may be associated with the alterations in percentage of TCD4 and TCD8 lymphocytes and TCD4/TCD8 ratio.