Before antibiotic development, Staphylococcus aureus was a cause of serious invasive infections such as sepsis and meningitis and claimed many lives. However, even after antibiotic development, S. aureus posed a new threat as a major nosocomial pathogen, changing it to methicillin-resistant S. aureus (MRSA) since 1961. This year marks the 50th anniversary of the first report on MRSA. Today, there are two classes of MRSA spreading in hospitals and the community. The United States experienced invasive MRSA epidemics in 2005, and the latter MRSA (named CA-MRSA), especially USA300, affected the entire United States. As a countermeasure, guidelines for the management of MRSA infections were prepared in 2011. In Japan, there are people who are suffering from "hidden" epidemics in the community, falling behind in fighting CA-MRSA. We summarized current epidemic MRSA and infections.