<p>A human leukocyte antigen-matched sibling is often the preferred donor in paediatric haematopoietic stem cell transplantation. However, ethical and legal concerns arise when the matched sibling is a minor, as the donor undergoes a medical procedure primarily for the benefit of another person and may be subject to significant familial and emotional pressure. In Malaysia, recently updated professional guidance addresses minor donor assent and independent advocacy. However, these provisions remain recommendatory rather than legally enforceable, and the guidance is silent on psychosocial assessment and post-donation care. This article examines how healthcare professionals in a Malaysian transplant setting understand and navigate the protection of minor sibling donors. Drawing on semi-structured interviews with 15 clinicians, nurses, and coordinators at a public hospital, the study identifies five interrelated themes: biologically driven donor selection, informal and inconsistent assent practices, constrained voluntariness within families, reliance on institutional discretion, and professional support for regulatory reform. The findings suggest that donor protection is shaped by a recipient-centred clinical framework in which safeguards are applied unevenly, inadequately documented, and largely dependent on local professional judgement. Using the Convention on the Rights of the Child, relational autonomy, and structural vulnerability as analytical lenses, the article explores how key safeguards such as assent, voluntariness, best interests, and donor welfare may be reduced from rights-based safeguards to matters of clinical discretion when they lack formal legal and institutional support. It argues that safeguards for minor donors, including independent advocacy external to the treating team, mandatory psychosocial assessment, and post-donation follow-up care, should be embedded within a binding regulatory framework rather than left to professional recommendation alone.</p>