Background and Research Objective: Health-related quality of life (HRQoL) is impaired in patients after a myocardial infarction (MI), and fatigue and depression are common health complaints among these patients. Patients' own beliefs about their illness (illness perceptions) influence health behavior and health outcomes. The aim if the present study was to examine illness perception and its association with self-reported HRQoL, fatigue, and emotional distress among patients with MI. Subjects and Methods: The sample consisted of 204 patients who had had MI and who completed the questionnaires during the first week in the hospital and 4 months after the MI. The questionnaires used were the Illness Perception Questionnaire, Multidimensional Fatigue Inventory, Hospital Anxiety and Depression Scale, and the Short Form Health Survey (SF-36). Results: Patient's illness perception changed over time from a more acute to a more chronic perception of illness, and beliefs in personal and treatment control of MI had decreased. Furthermore, these negative beliefs were associated with worse experiences of fatigue and lowered HRQoL. Conclusions: Patients' illness perceptions influence health outcomes after an MI. Supporting MI patients in increasing their perception of personal control could be a primary nursing strategy in rehabilitation programs aimed at facilitating health behavior, decreasing experiences of fatigue, and increasing HRQoL.