This study explores the underlying belief values influencing attitudes to posthumous organ donation, intention to sign a donor card as a sign of behavioural willingness. Extending the Theory of Reasoned Action this study integrates four external explanatory belief factors, altruism, perceived benefit, perceived risk and familial subjective norm to more fully explain organ donation intentions to sign a donor card. The data was collected from a convenience sample of 423 via an online questionnaire. The relationships between the constructs of the proposed conceptual model were tested using SEM and bias correct bootstrapping techniques. Several alternatives models were compared to confirm the mediation effects. Findings provide critical insight for marketers to design and implement culturally relevant strategies promoting the acceptance of posthumous organ donation. The contribution of this paper stems from the simultaneous modelling of a range of mediation effects which can better help explain people’s organ donation decision-making processes.