Background: this study aimed to assess parental knowledge and attitudes on childhood immunization among Saudi parents. Methods: this was a cross sectional prospective study. Pretested well designed questionnaires were distributed during March 2017. Parents with children of 0-12 years old were invited to answer the questionnaires. Association between dependent variables (knowledge, and attitudes) and independent ones (parent's demographics) were tested using Chi-square test. P values of < 0.05 were considered statistically significant. Results: a total of 731 parents were recruited. Parents had good knowledge on aspects related to the general role of vaccination in prevention of some infectious diseases were 672(91.9%), timing of the first dose in vaccination schedule included 635(86.9%). However, poor knowledge was documented among parents in other aspects like the importance of administration of multiple doses of the same vaccine to child immunity were 304(41.6%), administration of multiple vaccines at the same time have no negative impacts on child immunity were 271(37.1%), vaccination of children against seasonal influenza were 334(45.7%) and contraindication to vaccination were 287(39.3%). Parents attitudes towards immunization was positive expect in some aspects related to vaccination side effects showed 316 (34.2%) and the probability of occurrence of diseases against which the child was vaccinated was 288(39.4%). Gender, residence and educational level were found to be significantly associated with both parent's knowledge and attitudes towards immunization. Conclusion: although parents had good knowledge and positive attitudes on some aspects related childhood immunization, gaps in both studied domains were identified. Educational interventions are needed to upgrade parent's knowledge with special emphasis on less educated and residents of rural areas.