AIMS AND OBJECTIVES: The aim of this study was to explore patients' illness perception of myocardial infarction four months after a myocardial infarction. BACKGROUND: An important task for research on recovery from myocardial infarction is to understand the factors that influence an individual's adherence to secondary preventive strategies. Perceptual, cognitive and motivational factors have been found to influence adherence to a secondary preventive regimen. METHOD: Twenty-five patients were interviewed four months after a myocardial infarction. In accordance with grounded theory methodology, data collection and analysis were carried out simultaneously. RESULTS: The findings can be understood in light of two core categories: 'trust in oneself ' vs. 'trust in others'; belief in one's own efforts to control the illness; and 'illness reasoning', lines of thought about illness identity. In searching for relationships, six categories describing variation in illness perceptions of a myocardial infarction emerged: (i) 'sign of a chronic condition - feasible to influence'; (ii) 'sign of a chronic condition - uncontrollable'; (iii) 'acute event that can recur - feasible to influence'; (iv) 'acute event that can recur - uncontrollable'; (v) 'unthinkable acute event'; and (vi) 'non-recurring acute event'. CONCLUSION: The more reflective patients perceived the heart attack as a sign of a chronic condition; they also devoted time for reasoning about the possible causes of their illness. This is in contrast to patients who were less reflective and viewed their myocardial infarction as an acute event, which they avoided thinking about. The findings contribute to our understanding of variation in illness perceptions. RELEVANCE TO CLINICAL PRACTICE: The examination of how individuals perceive myocardial infarction may help health-care professionals individualize secondary preventive strategies, thereby improving adherence to health-care regimens. Nurse-patient discussions could begin with identification of the patient's variations of reflectiveness concerning his/her illness.