We characterized the oxidative stress response of Candida glabrata to better understand the virulence of this fungal pathogen. C. glabrata could withstand higher concentrations of H 2 O 2 than Saccharomyces cerevisiae and even Candida albicans . Stationary-phase cells were extremely resistant to oxidative stress, and this resistance was dependent on the concerted roles of stress-related transcription factors Yap1p, Skn7p, and Msn4p. We showed that growing cells of C. glabrata were able to adapt to high levels of H 2 O 2 and that this adaptive response was dependent on Yap1p and Skn7p and partially on the general stress transcription factors Msn2p and Msn4p. C. glabrata has a single catalase gene, CTA1 , which was absolutely required for resistance to H 2 O 2 in vitro. However, in a mouse model of systemic infection, a strain lacking CTA1 showed no effect on virulence.