Background and Objectives: Determining and monitoring the age at myocardial infarction (MI) and its comparison in various regions is one of the vital and basic principles for the management of MI. This study was conducted to determine the age at the first MI in Iran. Methods: In this cross-sectional, analytical study at a national level, the data of 20750 new MI patients registered in 2012 in 31 provinces of Iran according to the cardiologist’s diagnosis, World Health Organization criteria, and the codes ICD10: 121-122 were used. The calculations were done using the Stata 12 software. Results: The mean±SD of age at the first MI was 61.2±13.4 years in all patients in Iran. Moreover, 15033 (72.4%) patients were male with a mean age of 59.6±13.3 years. The mean age at MI in men was lower than women (65.4±12.6 years), showing a statistical significance (P<0.001).The mean age at MI was different among Iran provinces, with a statistical significance (P<0.001). The lowest mean age at the first MI was seen in the patients living in Semnan (59.1±12.9 years), followed by Tehran (60.4±13.5 years), Sistan va Balouchestan (60.3±13.9 years), and Lorestan (60.1±14.5 years), with a significant difference from the mean age of the patients in Ardabil (63.2±15.1 years) and Zanjan (64.4±112.8 years) (P<0.019). Conclusion: Our study demonstrated that the age at MI was approximately five years younger in men than women. This studyprovided the ground for monitoring the age at MI, and more effective management of cardiovascular diseases in Iran
