Background: Moral distress is common in neonatal intensive care unit (NICU) nurses. Purpose: The purpose of this study was to evaluate the relationships between NICU nurses' moral foundations, moral emotions, and moral distress. Research design and method: This is an observational cross-sectional self-report questionnaire study. Participants and research context: One hundred and forty-two (24%) of 585 Level 3-4 NICU nurses completed pen-and-paper self-report measures of moral foundations (harm, fairness, ingroup, authority, and purity) (Moral Foundations Questionnaire-20), proneness to self-conscious moral emotions (guilt and shame) (modified Personal Feelings Questionnaire-2), and moral distress (futile care, compromised care, and untruthful care) (modified Revised Moral Distress Scale). Ethical considerations: Participation was voluntary and anonymous. The ethics committees of the participating hospitals approved the study protocol (HREC Reference: LNR/18/SCHN/316). Results: Non-parametric statistical analyses showed medium to large correlations between moral foundations and moral emotions. Moral foundations and moral emotions had trivial to small correlations with moral distress. Using a liberal p-value of <.10 for statistical significance because of the small sample size, harm (rs = 0.22) and fairness (rs = 0.16) predicted futile care, ingroup predicted compromised care (rs = 0.19) and untruthful care (rs = 0.15), and purity predicted untruthful care (rs = 0.15). Guilt-proneness predicted futile care (rs = 0.15). Shame-proneness did not predict moral distress. Conclusion: The correlations between moral foundations and moral emotions were significant. Moral foundations and guilt-proneness predicted one or more dimensions of moral distress. The smaller than expected effect sizes may have been owing to how moral foundations, moral emotions, and moral distress were conceptualized and measured, or to moral disengagement, including NICU nurses' possible reluctance to countenance aversive but morally warranted feelings of guilt and especially shame. Understanding the nature of these relationships may complement the efforts of NICU administrators, educators, counsellors, and nurses themselves to mitigate moral distress.