To investigate the role of Cat1 overproduction in Candida albicans.Strains overproducing the CAT1 gene were constructed.Cells overproducing CAT1 were found to be more resistant to some oxidants and mammalian phagocytic cells. They also showed reduced intracellular reactive oxygen species generated by amphotericin B or ciclopirox olamine. CAT1 overproduction did not change the minimum inhibitory concentration of fungal cells to fungistatic or fungicidal azoles nor to amphotericin B although increased twofold the minimum inhibitory concentration to caspofungin. The role of Cat1 overproduction in virulence and colonization was also analyzed in mouse models.The overproduction of Cat1 protects against oxidants, phagocytes and certain antifungals at subinhibitory concentration but does not increase virulence in a systemic infection mouse model.