Due to the unique nature of the neonatal intensive care unit (NICU) and its moral distress, this study aimed to investigate moral distress in the NICU. This cross-sectional study was conducted on 234 physicians and nurses working in the neonatal wards of eight hospitals. The Corley’s Moral Distress Scale was used to collect data. Findings showed that 25 of the participants were physicians and 209 were nurses. The intensity and frequency of distress among physicians and nurses were assessed as moderate. The mean intensity and frequency of moral distress among nurses and physicians were 48.3%, 41.5% and 46.46%, 15.62% respectively. The results showed that the mean intensity and frequency of distress were higher, however not significantly, among nurses. The intensity and frequency of moral distress had a statistically significant and direct correlation with the intention to leave and the number of staff in each working shift among the nurses. Moral distress in the NICU practitioners was moderate, so addressing this issue and trying to alleviate it was important. Identifying the causes behind moral distress can help adopt appropriate measures to prevent and reduce them.