Objectives: To investigate breastfeeding intentions, attitudes, and knowledge among medical students at the University of Split School of Medicine, and the association with phase of study, additional breastfeeding education and gender. Subjects and methods: This cross-sectional study was conducted at the University of Split School of Medicine from 1st March to 28th April 2023, using online and written questionnaires. All medical students studying in Croatian who did not have children were eligible to participate. The questionnaire consisted of 68 questions. Descriptive statistics, t-test, Mann-Whitney U test, and Spearman's correlation coefficient were used. Results: A total of 357 ( 64.09%) medical students participated. Preclinical students exhibited nonsignificantly more positive intentions and attitudes, while clinical students had nonsignificantly better knowledge about breastfeeding. Students who attended the elective ''Breastfeeding Medicine'' demonstrated significantly more positive attitudes (P=0.010) and nonsignificantly better knowledge about breastfeeding, whereas students who did not receive additional breastfeeding education displayed nonsignificantly more positive intentions. Female students had significantly more positive attitudes (P<0.001) and nonsignificantly better knowledge, whereas male students expressed significantly more positive intentions towards breastfeeding (P=0.002). Students with higher grade point averages (P=0.050), those who were breastfed for a longer duration (P<0.001), and those who had the opportunity to observe a woman breastfeeding (P<0.001) exhibited more positive intentions, attitudes, and better knowledge about breastfeeding. Medical students possessed good knowledge about breastfeeding but harbored prejudices against breastfeeding beyond one year and breastfeeding in public and in the workplace. Conclusions: There is a need for additional breastfeeding education at the University of Split School of Medicine, particularly regarding the importance of breastfeeding beyond the first year of life and the risks associated with feeding infants cow's milk-based formula. To address this educational need, a curriculum focused on the importance of breastfeeding and dispelling existing prejudices should be designed and implemented.