We determined concentrations of selenium, zinc, magnesium, calcium, potassium, total and high-density lipoprotein cholesterol, and total creatine kinase (EC 2.7.3.2) in plasma (P) and (or) erythrocytes (E) of 32 men at the time of hospital admission for acute myocardial infarction and then on subsequent days 2, 3, 6, 10, and 12. During these 12 days, only P-selenium and high-density lipoprotein cholesterol concentrations remained unchanged. For the other variables, individual comparison of means indicated the dates of significant changes in concentration (p less than 0.05).