We aimed to study the effect of iron deficiency anemia (IDA) on immunity. In 32 children with IDA and 29 normal children, the percentage of T-lymphocyte subgroups, the level of serum interleukin-6 (IL-6); and the phagocytic activity, the oxidative burst activity of neutrophils and monocytes and the levels of immunoglobulins were compared. There was no difference in the distribution of T-lymphocyte subgroups. The mean IL-6 levels was 5.6+/-3.9 pg/ml in children with IDA and 10.3+/-5.3 pg/ml in the control group (P<0.001). The percentage of neutrophils with oxidative burst activity when stimulated with pma was 53.4+/-32.7% in children with IDA and 81.7+/-14.3% in the control group (P=0.005). The percentage of monocytes with oxidative burst activity was 13.8+/-11.7% in children with IDA and 35+/-20.0% in the control group (P<0.001) when stimulated with pma. and 4.3+/-3.1 versus 9.7+/-6.0% (P=0.008) when stimulated with fMLP. The ratio of neutrophils with phagocytic activity was 58.6+/-23.3% in the anemic group; and 74.2+/-17.7% in the control group (P=0.057). The ratio of monocytes with phagocytic activity was 24.3+/-12.0% in the anemic group; and 42.9+/-13.4% in the control group (P=0.001). IgG4 level was 16.7+/-16.6 mg/dl in children with IDA and 51.8+/-40.7 mg/dl in healthy children (P<0.05). These results suggest that humoral, cell-mediated and nonspecific immunity and the activity of cytokines which have an important role in various steps of immunogenic mechanisms are influenced by iron deficiency anemia.