Introduction: Children immunization, as a form of specific prevention, is conducted according to the mandatory vaccination calendar, in the Republic of Srpska. Vaccination status data are written in the health charts, immunization charts, and other health records. Objective: Inquire after the attitudes and knowledge of the parents of children up to eighteen years of age, on the matter of vaccination and search for the factors influencing their attitudes. Methods: Cross - sectional study included 300 parents. The research was performed in County outpatients' clinic, Bjeljina (central object and six larger remote clinics), by the family medicine teams of Educational center, during March 2015. Survey was anonymous and the questionnaire was specifically made for this purpose. Results: Out of the total number of the participants, 218 were females and 82 males; the majority of the parents lived in the country, 173, and 127 lived in the city. Participants' residence played an important role and it showed a statistically significant difference concerning these issues: whether the vaccination was necessary if the disease was eradicated (p=0.003), should the children with chronic diseases get vaccinated (p= 0.050), should parents buy the vaccine if it's recommended by a doctor even if it's not covered by health insurance (p= 0.002). The majority of the participants (96.3%) believe that children being vaccinated regularly is useful, 1.7% were not quite sure and 2% disagreed with the statement. Participants' residence was not of the significance when it came to their opinion on the vaccine's benefit. Conclusion: The majority of the participants have got a positive attitude towards vaccination. Physicians should use scientifically proven arguments to reassure parents who have doubts or refuse to have their children vaccinated.