This study aimed to investigate co-morbidity and coping strategies among older patients who suffer from different levels of posttraumatic stress disorder (PTSD) following myocardial infarction. Ninety-six older myocardial infarction (MI) patients were recruited from two general practices and completed the Posttraumatic Stress Diagnostic Scale (PDS), the General Health Questionnaire-28 (GHQ-28) and the COPE Scale. Ninety-two older patients with no previous MI experience constituted the control. Using the PDS, 30, 42 and 28% had full, partial and no-PTSD respectively. There were significant differences between the patient groups and the control on all GHQ-28 sub-scales. Significant differences were also identified between the patient groups in the following coping strategies: seeking emotional social support, suppression of competing activities, restraint coping, focusing on and venting of emotion, mental and behavioural disengagement. Controlling for bypass surgery, previous mental health difficulties, angioplasty, heart failure and angina, MANCOVA results did not change the overall results of the GHQ-28 but changed the results of coping in that seeking emotional social support and behavioural disengagement stopped being significant. Coping was a partial mediator between different levels of post-MI PTSD and co-morbidity. Depending on the severity of PTSD symptoms, co-morbidity and coping strategies can vary among older patients. Older patients with full-PTSD tend to use both maladaptive coping strategies as well as problem-focused coping.