Today, methicillin-resistant Staphylococcus aureus (MRSA) is a feared cause of nosocomial infections worldwide. These organisms can gain increased resistance to antimicrobial agents through biofilm formation, which appears to be a bacterial survival strategy. MRSA isolates obtained from patients were cultured in nutrient-limited medium supplemented with 0.2% glucose in aerobic, anaerobic, and CO2 incubation atmospheres. Biofilm formation was quantified by the microtiter plate test. MRSA strains showed significantly lower biofilm production when grown in an aerobic atmosphere compared to that exhibited in CO2-rich environments. Gaseous conditions and growth in a nutritionally limited medium can profoundly influence the amount of biofilm formation in MRSA. This should be considered in any in vitro study of in vivo behavior.