This study was carried out to identify the behaviour of Escherichia coli O157:H7 and of Listeria monocytogenes inoculated in Maronesa breed beef with different ultimate pH (pHu) (Normal and DFD), and stored at two different temperatures (4 and 9 ºC), during 28 days post mortem (pm). The main objective was to illustrate the problematic feature of dealing with beef meat showing high pHu and stored at mild abusive temperatures (9 ºC). Beef steaks (ms. longissimus dorsi) were inoculated with low levels (ca. 2 or 3 log CFU/g) of these both pathogens and packed in air, vacuum and three gaseous mixtures with decreasing O2 and increasing CO2 concentrations (MAP70/20, MAP50/40 and MAP30/60). At 4 ºC, the growth of E. coli O157:H7 presented the same pattern on Normal and DFD meat. On contrary, the growth of L. monocytogenes was higher on DFD meat, revealing the effect of the pHu and its psychotropic character. At abusive temperature, both pathogens grew, achieving high levels on DFD meat. In these cases, the MAP with the highest CO2 concentration (60%) revealed to be more effective against the development of E. coli O157:H7, presenting the lowest number of counts.