Introduction: Dysphoric Milk Ejection Reflex (D-MER) is a condition characterized by a sudden onset of dysphoric feelings immediately before milk ejection from the breast. Many healthcare professionals may confuse this phenomenon with postpartum depression, highlighting the importance of educating both healthcare providers and women about this condition. Objective: The main aim of this research was to assess midwives' knowledge about D-MER. Other objectives included determining the level of knowledge based on educational qualifications, years of work experience, and attendance at breastfeeding education in the past two years, as well as identifying the most common source of information about D-MER. Participants and Methods: The online survey included 77 midwives, of whom 28 (36.36%) had secondary education, and 49 (63.64%) had higher education. The questionnaire contained 17 questions, three of which were related to describing the sample, and the remaining 10 assessed knowledge about D-MER. The maximum score on the knowledge test was 10 points. Results: The average knowledge level about D-MER among midwives was M = 6.66 (SD = 1.501). Midwives with higher education had statistically significantly greater knowledge compared to those with secondary education (U = 497.500, p = 0.047). Knowledge about D-MER was statistically significantly positively correlated with years of work experience (ρ = 0.34, p = 0.002). No statistically significant difference was found in the knowledge of midwives who attended breastfeeding education in the past two years compared to those who did not (U = 587.500, p = 0.256). The most common source of information about D-MER was formal education. Conclusion: The results indicated that midwives generally have insufficient knowledge about D-MER. Midwives with higher education and more years of experience have more knowledge than those with secondary education and less experience. This is the first study of its kind in the Republic of Croatia, and its findings may contribute to improved education for both women and midwives about D-MER as a breastfeeding issue.