Abstract Issue Migration carry out risk of disrupting the epidemiological well-being among refugees and host populations. Since the beginning of Ukraine crisis over 50 000 refugees remain in Bulgaria; 92% are women and children. There is suboptimal childhood immunization coverage among Ukrainian refugee community prior to arrival in Bulgaria. Description of the problem Childhood vaccination is mandatory in Bulgaria for TB, hepatitis B, diphtheria, tetanus, pertussis, poliomyelitis, rubella, measles, mumps, Haemophilus influenzae B and pneumococci. Refugees with uncertain immunization status are vaccinated according to the national immunization schedule and receive personal immunization card. As of March 2024, we conducted cross-sectional study to assess knowledge and attitudes of Ukrainian mothers through an interview. Results Of 105 mothers interviewed, 72.38% were with higher education. Arrived women were not familiar with Bulgarian health system and especially with vaccination. Absence of language barrier and presence of doctors among them facilitated our study.56.19% believe that migration has disrupted their children’s vaccinations. 56.19% consider that migration has disrupted their children’s vaccination. Aware of benefits of vaccines were 91,43%, they mainly trust doctors-84.76%, they pay attention to the positive discussion in the media-55.77%.Mothers realize the importance of herd immunity, considering that vaccinated children protect the others-68.57%.Leading reasons for mistrust of vaccines, mothers indicate - doubt in favor of vaccine-24.76%, medical contraindications for child-21.90% and doubts about quality of the vaccine-19.05%.They pay attention to positive discussion in the media-55.77% and have confidence in Bulgaria’s institutions. Lessons The Government of Bulgaria provided significant support and medical care for the prevention of vaccinepreventable diseases among Ukrainian children. Institutions and volunteers work for successful integration of refugees. Key messages • Need to know the immunization status of Ukrainian children admitted to Bulgaria. • Increasing trust in vaccines and the health system in general in Bulgaria requires additional explanatory campaigns among refugees.