Introduction: Behavioral determinants can enable or hinder motivation towards registration and donorship and, subsequently, action or inertia towards organ donation. Nevertheless, there is limited information about the role of self-efficacy in relation to organ donation awareness and presumed consent among individuals and their families. The aim of this study was to explore knowledge, attitudes and general self-efficacy as behavioral determinants for organ donation among rural primary care attendants, in order to tailor awareness strategies for reversing inertia within an opt-out system. Methods: This was a prospective face-to-face survey during regularly scheduled appointments of 203 attendants at a rural primary care unit in northern Greece. Responses to a 12-item adapted 'Organ donation awareness' questionnaire measuring knowledge, attitudes and awareness were related to participants' General Self-Efficacy (GSE) Scale score. Hierarchical modelling of a multiple linear regression model was adopted with GSE score added. Results: About one-third of respondents (34.0%) had discussed presumed consent with a partner, family member or friend. More than half (54.2%) were concerned that donated organs might be used without consent for other purposes, such as medical research. A total of 30% found organ donation unacceptable because of religious beliefs. Organ donation awareness was not influenced by respondents' specific characteristics, but was significantly related to the GSE score (standard ß=0.155, p=0.033). Conclusion: Overall, organ donation perceptions among rural primary care recipients were determined by knowledge of the presumed consent procurement system, pre-conceptions, religious beliefs, altruism and GSE scores. The association of self-efficacy with raised awareness could potentially explain the gap between high intent to consent as a donor and subsequent lack of followup action. Further comparative research across behavioral determinants between rural/urban groups is needed in order to tailor awareness strategies suitable for an opt-out system.