Introduction: Self -efficacy is considered one of the key components of breastfeeding success and thus is important to explore. However, this requires reliable measuring tools. Goal: The aim of the study was to evaluate the psychometric properties of the BSES-SF as a measure of confidence in breastfeeding among Slovak mothers, and to determine the self -efficacy of mothers in breastfeeding and its related factors. Methods: The research was designed as a quantitative cross-sectional study. The sample consisted of 678 women who were on the 3rd- 4th day after delivery. A Slovak version of the 14 -item Breastfeeding Self -Efficacy Scale - Short Form (BSES-SF) was used to assess breastfeeding self -efficacy. Results: Cronbach's alpha of the Slovak version of the BSES-SF was 0.812. CFA has shown that the four -factor model of the BSES-SF offered the best fit for Slovak data. Education (p < 0.001), previous breastfeeding experience (p = 0.015), and skin -to -skin contact (p < 0.001) were shown to be statistically significant factors related to breastfeeding self -efficacy of mothers. Conclusion: The Slovak version of the BSES-SF has shown good psychometric properties and it can be recommended to assess the breastfeeding self -efficacy of mothers in Slovakia. The proven factors related to self -efficacy show the need for individual help, especially for women with higher education, women with a previous negative experience with breastfeeding, and the importance of skin -to -skin contact support.