– Streptococcus thermophilus CNRZ368 is an anaerobic aerotolerant bacteria and its ability to survive under aerobic growth conditions raises the question of the existence of a putative defence system against oxidative stress. Thus, survival of CNRZ368 in the presence of increasing concentrations of hydrogen peroxide was studied. Moreover, the influence of the physiologic state of the cells, as well as that of a preexposition with sublethal doses of hydrogen peroxide, upon S. thermophilus CNRZ368 survival were determined. The results suggest that S. thermophilus displays a defence system against oxidative stress and that this system is inducible.  2001 Éditions scientifiques et médicales Elsevier SAS hydrogen peroxide / oxidative stress / S. thermophilus CNRZ368