OBJECTIVE : Palliative care providers may be exposed to numerous detrimental psychological and existential challenges. Ethical issues in the healthcare arena are subject to continual debate, being fuelled with ongoing medical, technological and legal advancements. This work aims to systematically review studies addressing the moral distress experienced by healthcare professionals who provide adult palliative care. METHODS : A literature search was performed on PubMed, Scopus, Web of Science and PsycINFO databases, searching for the terms 'moral distress' AND 'palliative care'. The review process has followed the international PRISMA statement guidelines. RESULTS : The initial search identified 248 papers and 10 of them were considered eligible. Four main areas were identified: (1) personal factors, (2) patients and caregivers, (3) colleagues and superiors and (4) environment and organisation. Managing emotions of self and others, witnessing sufferance and disability, caring for highly demanding patients and caregivers, as well as poor communication were identified as distressing. Moreover, the relationship with colleagues and superiors, and organisational constraints often led to actions which contravened personal values invoking moral distress. The authors also summarised some supportive and preventive recommendations including self-empowerment, communication improvement, management of emotions and specific educational programmes for palliative care providers. A holistic model of moral distress in adult palliative care (integrating emotional, cognitive, behavioural and organisational factors) was also proposed. CONCLUSIONS : Cognisance of risk and protective factors associated with the moral distress phenomenon may help reframe palliative healthcare systems, enabling effective and tailored actions that safeguard the well-being of providers, and consequently enhance patient care.