Objectives. To use a theory of planned behaviour (TPB) framework to explore the beliefs underlying communication of the donation decision for people who had not previously registered their consent on a donor register or discussed their decision with significant others. Design. Initially, a focus group study elicited the common TPB (behavioural, normative, and control) beliefs about registering and discussing the organ donation decision. The main study assessed the important TPB belief predictors of intentions to register and discuss the donation decision. Method. University students and community members from Queensland, Australia (N = 123) completed items assessing their intentions and the TPB behavioural, normative, and control beliefs for registering and discussing their donation decision. Results. Structural equation modelling (SEM) analyses revealed significant paths between people's intentions to register their donation decisions and underlying behavioural (e.g. enabling efficient donation procedures), normative (e.g. friends, doctors/medical professionals), and control (e.g. lack of motivation, knowing details about transplant recipients) beliefs (R2=.30). There were also significant paths between people's intentions to discuss their donation decision and underlying behavioural (e.g. feeling uncomfortable talking about death related topics) and normative (e.g. partner/spouse, family members) beliefs, but not control beliefs (R2=.33). There was a significant path between intentions to register and intentions to discuss one's donation decision. Conclusions. Results highlight the importance of focusing on behavioural and normative beliefs about communicating the donation decision, specifically for people who have not previously communicated their decision, and suggest potential targets for interventions designed to promote decision communication.