In this work the effect of deformation of metastable austenite on its subsequent isothermal decomposition in bainite regions was investigated in three chromium steels with varying carbon contents. Four different types of treatments were used and the effect of carbon content was studied. Results of the kinetic measurements and of structural changes showed that the most important feature of these treatments was formation of narrow ferrite strips along the slip bands in austenite, which preceded formation of bainite of the usual morphology. A marked dependency of this ferrite strips formation on temperature suggests that the over-all transformation would strongly depend on deformation and recovery processes in austenite and on their mutual relation. A new qualitative model of the bainite transformation in deformed austenite is presented.