The study aimed on the study of pattern of exposure and immunological responses to varicella-zoster virus (VZV) infection. Methods: A seroepidemiological study was carried out on 92 blood samples collected from children in primary health care centers and outpatient clinics of Al-Sader Teaching and Basrah maternity and children hospital during the period from January 2007 till March 2008. Serological responses were investigated by an enzyme-linked immunosorbent assay (ELISA) to detect VZV IgG antibody and cellular responses was detected by Erythrocyte rosette (E-Rosette) formation test. Results: The overall VZV- antibody prevalence was 53.3% for both serologic and cellular responses. The degree and pattern of exposure to VZV cases plays important role in the seroconversion and responses to VZV infections. The greatest responses observed in those with direct contact (household) with chickenpox cases (68.6% and 74.3%) and the direct contact acquired from VZV infected mothers (80% for both serologic and cellular responses). Exposure to typical chickenpox cases confers higher serologic and cellular responses (75% and 94.4% respectively). Cellular responses to VZV infections lasted longer than that for serologic responses. Sever VZV infections confers significantly higher levels of immunity (100%) and the complication post VZV infections (Pneumonia and encephalitis) mostly associated with sever cases at earlier age groups rather than the mild VZV cases. The differences in immune responses to VZV infections between male and females was significant (P<0.05). The rates of exposure to VZV infections in urban areas are significantly higher than in rural areas (P<0.05). There was a significant decline in VZV immunity over time post infections and losses of protective immunity levels were quite evident few years post infection which stress the need for vaccination.