Background: MRSA is typically acquired nosocomially by patients with predisposing risks. Community-acquired (CA) infections are infrequent. Having observed several children hospitalized with CA MRSA infection, we sought to define the scope of the problem by reviewing medical records of all children with Staphylococcus aureus (SA) isolated from any site in 1993-5. For comparison, we reviewed charts of all those who had MRSA isolated in 1988-90. Methods: An isolate was defined as CA if the culture was obtained ≤ 72 h after hospitalization and the patient did not have risk factors for MRSA including prior hospitaization or antimicrobial therapy within the last 6 mo. Each SA isolate was determined to be colonizing or associated with clinical disease. Susceptibility testing was done by Vitek Auto Microbic System and/or disc diffusion. Available MRSA blood isolates in 1993-5 were characterized by pulse field gel electrophoresis (PFGE).Results: For 1993-5, 298 charts were reviewed, (57 and 241 charts from patients with MRSA and methicillin susceptible (MSSA) isolates, respectively); for 1988-90 30 charts were reviewed from patients with MRSA. The percentage of CA MRSA isolates increased from 3.3% in 1988-90 to 46.4% in 1993-5 (p=0.001). 74% of MRSA and 60% of MSSA isolates in 1993-5 were associated with disease. Among the CA disease isolates, the disease spectrum was not different when stratified by methicillin resistance. Cellulitis accounted for 48% and 43% of patients with MRSA and MSSA, respectively; abscesses accounted for 30% and 28% and pneumonia accounted for 13% and 9%, respectively. Irrespective of methicillin resistance, the disease spectrum among the nosocomially acquired SA infections differed from the CA disease spectrum; for example, bacteremia was most frequent, accounting for 21% and 37% of MRSA and MSSA disease isolates, respectively. Nosocomial MRSA had higher rates of resistance to clinda, TMP-SMX, erythro, and gent (p≤ 0.02) than did CA MRSA. Among 7 isolates subjected to PFGE, there were three patterns suggesting that a single MRSA clone was not responsible for the increased prevalence. Conclusion: The prevalence of CA MRSA infections has increased dramatically in our pediatric population. The disease spectrum of CA MRSA infection is similar to CA MSSA infection. CA MRSA were less often multiply resistant than nosocomial MRSA isolates.