Mother′s own milk is the best nutrition for infants. Its composition satisfies all children needs. Human donor milk is recommended for children who do not receive breast milk. This recommendation is supported by the United Nations Children′s Fund and the World Health Organization. Donor human milk is recommended as a substitute for breastmilk. In Croatia, there is only one human milk bank which is located in Clinical Hospital Centre Zagreb. The main purpose of the bank is to provide sufficient human milk for all preterm children in Croatia. The main objective of this research is to investigate the attitudes of pregnant and breastfeeding women toward breast milk donation. Data were collected using an online questionnaire created specifically for this research and participants were recruited on a social network dealing with breastfeeding issues. 598 respondents participated. The main results of this research show that the majority of respondents are willing to donate breast milk. No association was found between attitudes toward donating breast milk and profession, education level, county of residence, parity, and satisfaction with support during breastfeeding. The most common sources of support during breastfeeding were breastfeeding support groups and family members. The results also show that there is no association between attitudes toward breast milk donation and altruism and attendance at antenatal classes on breastfeeding. Donors are the most important factor in the successful operation of human milk banks, so it is extremely important to study potential donors' attitudes toward donating breast milk. The results of this research indicate that the attitudes of potential donors are extremely positive and that there is a need to explore the barriers to milk donation in order to provide sufficient quantities of human milk for all children who need it.