Irradiation of ground beef in modified atmosphere packaging was compared with irradiation of ground beef in vacuum packaging for the inhibitory impact on Escherichia coli O157:H7. Recovery of surviving organisms showed that packaging systems did not alter the effects of irradiation for reduction of E. coli O157:H7 in ground beef. Therefore, modified atmosphere packaging may be used to improve color of irradiated ground beef without affecting the inhibitory impact of irradiation.