OBJECTIVES: Several reports have already proved that the number of deaths related to acute myocardial infarction (AMI) shows a seasonal variation, with a peak in winter, and a lowest rates during the months of summer. The effects of meteorological variables on the human organism have been studied for more than fifty years, and changes in the number of AMI events have been related to both cold or warm temperatures. METHODS: The number of cardiac mortality (N=16.160) in Hungary shows a steadily decreasing tendency between 2000 and 2005, with a seasonal variation regardless of age or sex. RESULTS: The peak period of AMI mortality was during the months of spring, with a lowest value during the summer. There was a significant difference between seasons (F=3.027; p<0.05). The daily average of cardiovascular mortality during each season was the following: 8.48 during spring, 7.23 during the summer, 7.79 during autumn, and 7.76 during winter. The sharp temperature increase during spring, and the similarly significant decrease of temperatures during autumn, both have an increasing effect on heart attack related mortality. Studying the moving-average of AMI mortality (k=7), and the relation with the daily average temperature of the preceding 7 days, we have found a medium value negative correlation (r = -0.466, p<0.01). Considering the moving average of deaths (k=7) and the average daily temperature of the preceding seven days above and below 20 Celsius, we have found a significant difference. CONCLUSIONS: The mortality of AMI may be related to the internal biological rhythm of the organism, and also to such external conditions as weather. The combined effect of certain meteorological factors, such as a sudden temperature or atmospheric pressure change, may be considered as a risk factor in the mortality of a heart attack.