The aim of the present study was to evaluate the trends in attack rate, incidence, recurrence and 28-day case-fatality of myocardial infarction (MI) in Kaunas population aged 25-64 during 1983-1998, according to ischemic heart disease register data. The source of data--Kaunas population-based ischemic heart disease register. Trends were analyzed using method of linear regression on logarithms of the age-standardized annual morbidity and lethality rates. The regression coefficient multiplied by 100 is given as an average yearly change. The age-standardized rates were calculated by the direct method and the world standard population was used as the standard. During the study period attack rates of MI remained stable in men. Among Kaunas men aged 25-64 years incidence rates of MI decreased statistically significantly, while MI recurrence rates had a tendency to increase during the study period. Among Kaunas women, both attack rates of MI and recurrence rates of MI were increasing statistically significantly, although MI incidence rates remained stable during 1983-1998. The MI 28-day case-fatality rates tended to decrease among both men and women. Further efforts of the primary prevention of the ischemic heart disease are required in order to achieve stable decreasing trends in both attack rate and incidence of MI in the middle-aged Kaunas population.