In the United States, more than 100.000 women younger than 65 years are diagnosed as having acute MI each year, which represents 21% of all acute MI cases in women (Circulation 2009; 119 (3): e21-e181). Previous studies have shown that women younger than 55 years have higher hospital mortality rates after acute myocardial infarction (MI) than men of similar age (Arch Intern Med 1998; 158 (18):2054-2062; NEJM 1998; 341 (4): 217-225; Ann Intern Med 2001; 134 (3): 173-181). This aspect is important and also raises one important question of why younger women have a higher risk of adverse events and mortality after MI than matched men (NEJM 1999; 341 (4): 275-76; Ann Intern Med 2001; 134 (3): 239-241). It is important to underline that many reports that examine mortality rates after MI by sex and age are based on patient populations enrolled decades ago. Now, excess mortality in younger women has decreased in recent years because of increasing awareness of heart disease in women, which may have translated into better diagnosis, treatment and outcomes (Circulation 2006; 113 (4): 525-534). The main purpose of this study is to describe temporal trends in the case fatality rates of MI according to sex and age during a period of approximately 12 years (June 1, 1994 – December 31, 2006). The study population has included 916.380 patients from the National registry of Myocardial Infarction with a confirmed diagnosis of MI. In hospital mortality decreased significantly between 1994 and 2006 in all patients but more in women than in men. The mortality reduction in 2006, related to 1994, has been largest in women younger than 55 years (52.9%) and lowest in men younger than 55 years (33.3%). In patients younger than 55 years the absolute decrease in mortality has been 3 times larger in women than in men (2.7% vs 0.9%). The excess mortality in younger women (<55 years) compared with men was less pronounced in 2004-2006 than it was in 1994-1995. The sex difference in mortality decreases in older person. In recent years women has experienced larger improvements in hospital mortality after MI than men. Mortality gap between younger women and men is largely attributable to temporal changes in risk profiles. Better awareness of heart disease in younger women in recent years or improved diagnosis or treatment could have reduced their risk profile compared with men (Circulation 2006; 113 (4):525-534; Circulation 2005; 111 (4):499-510). These are the limitations of the study: the authors had data on in-hospital mortality; the results may not be extrapolated to long-term; information about the use of statins has not been available in the registry.