Infections of the respiratory tract are very common in young children. They may affect the quality of life and have a great economic impact. On the other hand, respiratory tract infections through MALT system play a positive role in the maturation and development of the immune system. The aim of the study was to examine quantitative and qualitative changes of T and B cells and granulocytes surface molecules in 24 children with recurrent (more than 8 episodes per year) infections of the respiratory tract and in 18 healthy children. The expression of CD2, CD3, CD4, CD8 on T cells; HLA-DR, CD19, CD5/CD20 on B cells, and CD11a/CD18, CD11b/CD18, CD62L, CD16 on granulocytes from peripheral blood was evaluated by a flow cytometry method. We observed a significant increase in the CD5+/CD20+ positive cells on B cells. We also observed a decreased expression of CD11c+/CD18+ cells, CD11a, and CD62L on granulocytes. The expression of other structures on lymphocytes and the CD11b/CD18+ on granulocytes remained unchanged. CD5+/CD20+ cells constitute a filogenetically old population responsible for the production of IgM of low specificity and affinity for specific antigens. The prevalence of this fetal phenotype population may be explained as a delayed maturation of the humoral immune system leading to increased susceptibility to infections. A lower percentage of CD11a may be related to the blockade of that molecule by rhinoviruses.