Mechanisms to sense, avoid and scavenge oxidants as well as repair damaged biomolecules are important survival and virulence factors of the obligate human pathogens Neisseria meningitidis and Neisseria gonorrhoeae. These bacteria are routinely exposed to several forms of oxidative and nitrosative stress during colonisation and interaction with the host, of which superoxide, hydrogen peroxide and nitric oxide are some of the key oxidants that result in damage to the bacteria. However, the pathogenic Neisseria express an array of defense mechanisms to combat oxidative and nitrosative stress, such as catalase, superoxide dismutase, nitric oxide reductase, as well as thiol-based defenses and proteins involved in metal homeostasis and repair of damage to DNA and proteins. The expression of these defenses is tightly regulated by a series of transcription factors containing redox-sensitive active sites, including OxyR, Fur, PerR/Zur, FNR, MseR, LexA NsrR, NmlR, which sense and maintain the redox homeostasis of the cell.