Immunodeficiency and infectious disease antibody reduction due to chemotherapy can increase the acquisition of infectious diseases and death. The aim of this study was to compare the level of immunity (diphtheria, tetanus, pertussis and hepatitis B antibodies) in children under chemotherapy and healthy children. In this descriptive-analytical study, 35 children with cancer who underwent chemotherapy (case group), and 90 healthy children (control group) were enrolled. Evaluation of specific antibody level against Corynebacterium diphtheriae, Bordotella pertussis, clostridium, tetanus, and hepatitis B was performed in two groups using enzyme-linked immunosorbent assay (ELISA). Data were analyzed by SPSS version 22 using descriptive statistics, chi-square test, and logistic regression model. The mean antibody titers of hepatitis B, diphtheria, and pertussis were significantly lower in case group (P < 0.05). There was a significant difference between the two groups in immunity level only for hepatitis B, with a lower level in the case group (P < 0.023). Significant, inverse correlation was found between age and antibody titers of hepatitis B (r = -0.48, P = 0.001) and pertussis (r = -0.22 and P = 0.01), and after adjusting for the effect of age by using logistic regression, the immunity levels of hepatitis B and pertussis vaccines were not significantly different between case and control groups (P > 0.05). The results of this study showed that the antibody titers were lower in the children under chemotherapy, and only in hepatitis B children, the immunity level was significantly lower in the case group than in the control group.