This study aimed to describe inpatients with myocardial infarction and their participation in care as documented in the nursing records when standardized care plans are used in care. The use of standardized care plans not only has increased the quality of medical treatment but has also overlooked patients' opportunities to participate in their own care. There is a lack of knowledge about how standardized care plans influence patients' participation in nursing care. Data were collected from thirteen patients' records with diagnoses of myocardial infarction. Participation in the decision-making process and participation associated with “sharing with others” were searched for in the analysis. The analytical process was guided by content analysis. The findings were grouped into two categories: patients' intermediary participation and patients' active participation. The main results indicated that patients' intermediary participation depended on healthcare professionals' power to rule the nursing care situation.