Bearing steels are heat treated to get martensitic microstructures providing high hardness necessary for good rolling contact fatigue performance. Without specific action taken, austenite is generally retained after heat treatment in the final component with a more or less important content. Depending on the requirements of each application, retained austenite can be desired because of beneficial effects such as improvement of rolling contact fatigue performance, mostly in contaminated lubricating conditions, or can be avoided if dimensional stability is needed for example in cases of bearings operating for long times at high temperatures. Because bearing steels are subjected to more and more demanding operating conditions, heat treatments and microstructures are engineered in terms of retained austenite in order to use the beneficial effect of a stabilized retained austenite, or on the contrary to suppress retained austenite. This paper discusses the advantages and shortcomings of retained austenite in bearing steels, with illustrations of work realized in NTN-SNR.