As part of the Danish WHO MONICA study, a register of patients with myocardial infarction was established in 1982, covering 11 municipalities in the western part of Copenhagen County, Denmark. During the period 1982-91, all cases of myocardial infarction among citizens aged 25-74 years were registered and validated according to the criteria set up for the WHO MONICA project. Short-term (28 days) and long-term (up to 15 years) survival in three periods were compared. The rate of mortality after a non-fatal myocardial infarction was compared with that of the general population, and causes of death were analyzed. Short-term survival did not change during the study period, whereas long-term survival improved for men but did not change for women. The excess mortality rate among female patients over that of the general population was due to ischemic heart disease, other cardiovascular diseases, cancer and other diseases. The excess mortality among male patients was due only to cardiovascular diseases.