Objective-To examine whether patients' initial perceptions of their myocardial infarction predict subsequent attendance at a cardiac rehabilitation course, return to work, disability, and sexual dysfunction. Design-Patients' perceptions of their illness were measured at admission with their first myocardial infarction and at follow up three and six months later. Setting-Two large teaching hospitals in Auckland, New Zealand. Subjects-143 consecutive patients aged under 65 with their first myocardial infarction. Main outcome measures-Attendance at rehabilitation course; time before returning to work; measures of disability with sickness impact profile questionnaire for sleep and rest, social interaction, recreational activity, and home management; and sexual dysfunction. Results-Attendance at the rehabilitation course was significantly related to a stronger belief during admission that the illness could be cured or controlled (t=2.08, P=0.04), Return to work within six weeks was significantly predicted by the perception that the illness would last a short time (t=-2.52, P=0.01) and have less grave consequences for the patient (t=-2.87, P=0.005), Patients' belief that their heart disease would have serious consequences was significantly related to later disability in work around the house, recreational activities, and social interaction, A strong illness identity was significantly related to greater sexual dysfunction at both three and six months. Conclusions-Patients' initial perceptions of illness are important determinants of different aspects of recovery after myocardial infarction, Specific illness perceptions need to be identified at an early stage as a basis for optimising outcomes from rehabilitation programmes.