Objective: Numerous studies have reported the weekly variation of an acute myocardial infarction. The Monday peek has been connected with higher rate of physical and mental, work-related stress. We wish to study the weekly variation of an acute heart attack in the group of workers and pensioners, and find out whether National Holidays on the first day of the week influence the weekly rhythm of a heart attack. Methods: We have carried out the retrospective analysis of patients received at Hungarian hospitals with the diagnose of an acute heart attack (n=88,687) between 2000 and 2005. Data were retrieved from the data-base of the National Health Insurance Fund in accordance with the International Classification of Diseases (ICD). Results: According to the morbidity data of a heart attack, the weekly peek is on the first work-day of the week, showing a gradually decreasing tendency until the end of the week. Morbidity rates on Mondays being National Holidays are similar to the number of events on Saturdays and Sundays (Z=-25,337; p<0.001). There was a significant difference between number of events on work-days and weekends (Z=-26,638; p<0.001). No marked difference has been found between workers under the age of 65 and pensioners above the age of 65, or between the two sexes. Conclusion: The results of our study reveal that the occurrence of an AMI shows characteristic changes through the days of the week, and the first work-days of the week may be related with higher incidence of a heart attack. Such results urge finding the potential new methods of forecast and prevention.