Declining trends in case fatality (CF) of MI events have been generally reported in western countries. It is, however, not clear whether the development has been equally beneficial in both sexes. Data from two large population based registers, FINAMI and the Finnish National Cardiovascular Disease Register (CVDR) were used to determine whether the CF of incident MI events has declined less in women than in men. All patients aged 35 and over were included. CF was calculated for different time periods after the onset of the MI event, the main emphasis was in pre-hospital, 28-day, and 1-year CF. Figures were compared between two study periods: 1994-1996 and 2000-2002. A total of 6,342 incident MI events were recorded in FINAMI and 117,632 events in CVDR during the study periods. Comparison between the two study periods showed that the CF was generally declining. However, a slower decline in short-term CF was seen among young (aged<55 years) women (P for sex by study period interaction in pre-hospital CF=0.028 in FINAMI and 0.003 in CVDR, and for 28-day CF P=0.016 in FINAMI and <0.0001 in CVDR). In conclusion, the short and long-term prognosis of MI events has improved in both sexes. Pre-hospital CF has declined less among younger women than among men and among older women. This slower decline in early CF was responsible for the slower improvement in 28-day and 1-year prognosis in young women.