To summarize recent international and national epidemiological data of methicillin-resistant Staphylococcus aureus (MRSA) colonization in ICU. Review articles using Medline, CDC (Atlanta, GA, USA) and IVS (St Maurice, France) databases (1994-2004): critical assessment of literature and data of MRSA colonization epidemiology in ICU. MRSA colonization varied from 3 to 14% on ICU admission. Five to twelve percent of patient acquired MRSA colonization during hospitalization. This reservoir is often unknown as clinical sample identifies only a part of MRSA colonization. The probability to develop an infection caused by MRSA in colonized patients is about 30%. Acquisition of MRSA in ICU patients is strongly and independently influenced by colonization pressure. Systematic screening for colonization on ICU admission and during hospitalization is essential for many authors to control the spread of MRSA. Other policies such as implementation of isolation precaution and antibiotic use also contribute to decrease the MRSA incidence rate observed for several years in French ICU.