From a randomized multicenter trial with metoprolol in suspected acute myocardial infarction (n = 5778) we report on the outcome during a one-year follow-up in patients with confirmed infarction (n = 4106) in relation to whether or not they developed Q waves. Patients with Q waves had another pattern of risk factors, including lower age and a lower occurrence of previous infarction, angina pectoris, and congestive heart failure. After one year follow-up, 14.3% of the patients with Q waves had died versus 9.0% of those without Q waves (p less than 0.001). Reinfarction during the first year occurred in 8.2% of patients with Q waves and 12.5% of patients without Q waves (p less than 0.001). After one year, other morbidity aspects appeared relatively independent of the original presence of Q waves. In conclusion, during the first year after development of acute myocardial infarction the appearance of Q waves during the first three days is associated with a higher mortality and a lower reinfarction rate, whereas other morbidity aspects appear to be relatively independent of its presence.