PurposeResearch has established the prevalence and relevance of moral injury in healthcare workers, though less attention has been paid to the different classes of potentially morally injurious events (PMIEs) experienced by this population and their impact. This exploratory study sought to examine the frequency of self- and other-generated PMIE classes and their associations with demographic characteristics and well-being outcomes among mental healthcare staff.Design/methodology/approachSecondary analysis of data drawn from two cross-sectional surveys of 267 frontline and leadership staff from mental healthcare settings in the UK was conducted. Responses on the Moral Injury Events Scale and the Short Professional Quality of Life Scale were extracted for analysis.FindingsBetrayal by others was most frequently endorsed (61.8%), whilst self-transgressions were least frequently reported (25.5%). After controlling for the number of PMIE classes experienced, betrayal significantly predicted secondary traumatic stress (p = 0.01) and burnout (p = 0.04). Additionally, other transgressions significantly predicted secondary traumatic stress (p = 0.008). The predictive effects of self-transgressions on burnout, secondary traumatic stress and compassion satisfaction were all nonsignificant after controlling for the number of PMIE classes experienced.Practical implicationsFindings highlight differences in the frequency and impact of self and other PMIEs experienced by healthcare professionals. Reducing cumulative exposure to differential PMIE classes appears to be of critical importance to improving occupational well-being in this group.Originality/valueTo our knowledge, this study is the first to explore the associations between PMIE classes and occupational well-being in a mental healthcare population, inclusive of frontline and leadership staff.