Background Time is crucial when an acute myocardial infarction (AMI) occurs, but patients often wait before seeking medical care. Aim To investigate and compare patients' and relatives' knowledge of AMI, attitudes toward seeking medical care, and intended behaviour if AMI-symptoms occur. Methods The present study was a descriptive, multicentre study. Participants were AMI-patients ≤ 75 years (n = 364) and relatives to AMI-patients (n = 319). Questionnaires were used to explore the participants' knowledge of AMI and attitudes toward seeking medical care. Results Both patients and relatives appeared to act more appropriate to someone else's chest pain than to their own. Patients did not have better knowledge of AMI-symptoms than relatives. Women would more often contact someone else before seeking medical care. A greater percentage of elderly (65–75 years), compared to younger individuals, reported that they would call for an ambulance if chest pain occurred. Conclusions There were only minor differences between patients and relatives, regarding both knowledge and attitudes. It seems easier to act correctly as a bystander than as a patient. Therefore, in order to decrease patients' delay time it is important to educate relatives as well as patients on how to respond to symptoms of an AMI