Aim: To synthesize and describe the emotional and psychological implications for healthcare professionals who provided care in a mass casualty incident or disaster. Background:The experience of healthcare providers immersed in the actual uncertainty of an ongoing disaster is real, challenging, complex and strongly connected with emotions. Identifying these implications for healthcare professionals is essential for developing strategies to help these professionals deliver high-quality care.Evaluation: A systematic review was conducted in PubMed, CINAHL, Scopus, Nursing & Allied Health Database and PsycINFO using published data until February 2021 and following the PRISMA guidelines.Key issues: Nineteen articles were included. Factors associated with negative psychological implications were identified and different strategies have been synthesized to prevent or reduce them when caring for the victims of a disaster.Conclusions: Feelings of sadness, helplessness, fear and blockage, among others, were identified as common reactions among nurses and other healthcare professionals dealing in mass casualties or disasters. These reactions may lead to post-traumatic disorder, turning professionals into hidden victims.Implications for nursing management: Organizations, senior charge nurses and other health service managers need to foster resilience and flexibility among their workforce to improve self-care during a disaster, as well as ensure policies to address a lack of emotional preparedness among their personnel. Some strategies to consider include cognitive behavioural therapy, psychoeducation or meditation.