BACKGROUND: Admission to the neonatal intensive care unit (NICU) is stressful for parents. Nurses often focus on maternal well-being and fail to acknowledge the stress of fathers. Research on fathers’ psychological stress is limited. PURPOSE: A systematic review of the literature was completed to examine the extent of psychological stress and types of stressors in fathers with infants admitted to the NICU. METHODS/SEARCH STRATEGY: A search of Ovid MEDLINE, Cochrane Library, PsycINFO, CINAHL, and EMBASE was conducted to identify descriptive and observational studies reporting father-specific stress in the NICU. Studies using observational and descriptive designs, published in English, and reporting father-specific stress outcomes during a NICU admission were eligible for inclusion. Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used for quality assessment. RESULTS: Fifteen studies met inclusion criteria. Fathers find the NICU environment stressful and are more stressed than fathers of full-term, healthy infants. Parental role alteration, infant appearance, NICU environment, and staff communication are stressors. IMPLICATIONS FOR PRACTICE/RESEARCH: By recognizing the extent and types of psychological stress in fathers, nurses can provide better support for fathers in their new role. Younger fathers and those with very low birth-weight premature infants may need additional support and resources. Future research on fathers’ stress should include larger sample sizes, diverse populations, and tool development and evaluation.