The objective of this study was to investigate the effects of modified atmosphere packaging (MAP) systems on shelf-life and quality of beef steaks with high marbling. Four packaging types were used including 80% O2 MAP (80% O2 + 20% CO2), 50% O2 MAP (50% O2 + 30% CO2 + 20% N2), carbon monoxide MAP (0.4% CO + 30% CO2 + 69.6% N2) and vacuum packaging (VP). Steaks were displayed under simulated retail conditions at 4 °C for 12 days. Purge loss, pH, color stability, oxidative stability and microbial counts were monitored. Aerobically packaged steaks exhibited a bright-red color at the first 4 days. However, discoloration and oxidation became major factors limiting their shelf-life to 8 days. Compared with aerobic packaging, anaerobic packaging extended shelf-life of heavily marbled beef steaks, due to better color stability, together with lower oxidation and microbial populations. Among all packaging methods, CO-MAP had the best preservation for steaks, with more red color than other packaging types.