- Background Immunization has a significant impact in protecting from severe diseases. Various factors that could influence child immunization coverage and parents' decisions about vaccinating their children should be further explored in specific population groups. Objectives The current study has two main objectives: to assess the main information sources that affect parental decisions to vaccinate their children and to measure the extent to which these factors differ demographically by exploring the opinions and attitudes within four main population groups in Israel: ultra-Orthodox Jews, all other Jews, non-Bedouin Arabs , and Bedouins. Methods 1504 parents, with similar representation among four main population groups, participated in this study. A structured, anonymous, self-administered questionnaire was used. Results The most influential source on parents' decisions to vaccinate their children was the nurse at Mother and Child Health Clinics (MCHCs). Positive attitudes were shown regarding the key role of immunization in preventing severe diseases, while the most important concern expressed was the potential pain to the child while being vaccinated (rather than the safety of the vaccine). Higher compliance rates were reported among participants with a non-academic education level (χ 2 = 12.21, p 2 = 26.66, p 2 = 5.13, p Conclusions The factor that most influenced Israeli parents' decisions to vaccinate their children was their degree of trust in information sources about vaccinations, particularly the nurses at the MCHCs.