['Coronary heart disease is the second cause of death in Chilean women, with higher mortality among women, especially at younger ages. The objective was to analyze in-hospital case-fatality by sex and age in patients with acute myocardial infarction in Chile and to evaluate associated factors.', 'From the nationwide hospital admissions database and the GEMI registry (a multicenter registry), we selected all cases of acute myocardial infarction (code: I.21) that occurred between 2001 and 2007 in Chile. We estimated odds ratios for in-hospital case-fatality in women by age (crude and adjusted for clinical characteristics and treatment).', 'In total, 49,287 cases of acute myocardial infarction were hospitalized, 31.3% of them women; 9278 patients were incorporated in the GEMI registry (27.1% women). In-hospital case-fatality was higher (P<.001) in women than men (national database, 20.4% vs 11.3%; GEMI, 14.2% vs 7.3%, irrespective of age. In-hospital case-fatality risk was higher in women aged<45 years: national odds ratio=2.3 (95% confidence interval, 1.5-3.3) and GEMI, odds ratio=2.7 (1.1-6.8). The estimated risk was lower in women aged 75 or more years in both databases, 1.3 (1.2-2.4) and 1.5 (1.2-1.9), respectively. Younger women less often received statins, odds ratio=0.7 (0.6-0.8); acetylsalicylic acid, odds ratio=0.4 (0.2-0.6); betablockers, odds ratio=0.8 (0.6-0.9), and thrombolytics, odds ratio=0.6 (0.5-0.8). An interaction was found between Killip class and sex. After adjusting for covariates, women aged<55 years with ST-segment elevation myocardial infarction and Killip class I-II, had the highest risk, odds ratio=4.3 (2.1-8.9).'] Do younger women have a higher risk of in-hospital mortality due to acute myocardial infarction in Chile?