Secondary prevention and self-management of coronary heart disease (CHD) are of major importance to people who survive myocardial infarction (MI). This can be facilitated by cardiac rehabilitation (CR; the formal health service programme) and informal CHD self-help groups. Non-participation is an important issue, yet it is poorly understood. Rehabilitation difficulties and prevention challenges have been identified among people following MI, but the particular experience and perspective of CR and CHD group non-participants are largely unknown. The study aimed to understand non-participation in CR and CHD self-help groups from the perspectives of the non-participants and to provide insight into their experience and that of their 'significant others' in rehabilitating in the absence of these resources. In-depth interviews were conducted with 27 people who had not participated in either hospital-based CR or a CHD group, 6-14 months post-MI, and 17 'significant others' in Lothian, Scotland. Factors influencing non-participation fell into three broad themes 'No need/no point', 'Not worth it', and 'Not possible'. In the latter two categories, non-participation in these resources was often considered a 'missed opportunity' and needs had remained unmet. Shifts between categories could occur over time. Non-participation was linked to rehabilitation difficulties for some people and family members. Recommendations to enhance post-MI support are made.