In this study, leukocyte, granulocyte, lymphocyte and monocyte count was evaluated in patients with iron deficiency anaemia. Complete blood count data from 84 patients (with iron deficiency anaemia) admitted to our hospital’s paediatrics and general medicine outpatient clinics, and 109 age- and sexmatched healthy controls, were evaluated retrospectively. Complete blood count analyses were performed with Micros 60, and serum iron and ferritin levels analyses were performed by auto analyzers. Whilst granulocyte count was higher in the group with iron deficiency anaemia, lymphocyte count was lower. No difference in monocyte count was found between the groups. Although total leukocyte count was higher in the group with anaemia, the difference was statistically insignificant. In anaemia, iron deficiency increases granulocyte but reduces lymphocyte count. The molecular basis of this dual effect of iron on cellular defence system is still, to a great extent, unexplained.