Objectives: The effect of educational intervention (EI) on the accuracy of breast cancer (BC) risk self-assessment and knowledge about chemoprevention was investigated. In addition, it was investigated how different participants’ characteristics like HL, general beliefs about medicines and self-reported health status influenced BC risk perception and BC chemoprevention knowledge and attitudes. Chemoprevention attitude was examined in a hypothetical situation. Study design: This was non-randomised controlled trial conducted in a single health centre in Croatia. Participants and Methods: 249 healthy women who attended Health Centre Osijek’s Department for Breast Diagnostics for screening mammography or diagnostic either mammography or breast ultrasound were recruited. Standardised questionnaires Health Literacy European Questionnaire 47, Beliefs about Medicines Questionnaire General, Short Form-36 were used. With questionnaire created for the purpose of this study (and validated) BC risk perception, knowledge about BC and chemoprevention and chemoprevention attitudes were examined at the recruitment point, immediately after the EI and one week after the EI. Educational interventervention in a form of a lecture was conducted and information leaflet was given to the participants. Results: Nearly 20% of participants underestimated own BC risk, including one-third of women with positive family history of BC in the close relative. Women who correctly estimated own lifetime BC risk were dominantly of excellent HL. Women with positive chemoprevention attitude had significantly more positive beliefs about medicines in the subdomain medicines overuse, worse general health perception and stronger role limitation due to emotional problems. Previous breast biopsy or personal history of AH did not contribute to higher interest in taking chemoprevention drug. No significant correlation between HL level and chemoprevention attitude was noted. Knowledge about chemoprevention and chemoprevention drugs significantly increased after the EI and was maintained one week later. In comparison to the control group, after the EI there was significantly more participants with neutral chemoprevention attitude: 40.2% vs 85% (2test, P<0.001). Also, significantly less participants had positive attitude immediately after the EI, in comparison to the control group: 12% vs 50% (2test, P=0.010, P<0.001). Interestingly, in the control group there were 12% of women with negative attitude, but 0% one week after the EI. Conclusion: The EI significantly increased knowledge about BC and chemoprevention. And it shifted the chemoprevention attitude towards more neutral. The EI did not have an impact on the accuracy of BC risk self-assessment.