This study examined the belief, knowledge and perception on parents to immunization of children in Lagos State. Questionnaires were distributed to a sample of 1000 parents seeking for their opinion on various issues pertaining to their perception about child immunization. In addition, the study did a general literature review on immunization coverage in Nigeria taking into cognizance the beliefs of the Yoruba of South-West Nigeria to which the study area (Lagos State) is an integral part. The result shows that although, many parents have knowledge about the efficacy of vaccination for their children, yet culture overrides such knowledge in some cases. The result shows that gender of parents does not significantly affect their belief about immunization and their willingness to present children for routine immunization. However, marital status, education and religion significantly influence such belief. It is concluded that the culture and beliefs of the Yoruba in Lagos State is too complex to be ignored in any public health plan, if such plan is to be effectively and efficiently implemented.