In this paper, the influence of Nb, Vand Ti on the peak strain of deformed austenite in Mo-based micro-alloyed steels has been studied. Four steels, identified as Mo, Mo+V, Mo+N b and Mo+Ti, respectively, were heated to 1200℃ and held for 10min and then the temperature was rapidly reduced to test temperatures and maintained for 40s. The test temperatures were 950, 1000, 1050, 1100, 1150 and 1200℃ at the strain rates of 0.05, 0.1, 0.5, 1 and 5s 1, respectively. Results indicate that the presence of Nb, Ti, and Vaffects significantly the value of peak strain (ep), especially Nb which has a significant effect on the start of the dynamic recrystallisation. For all the steels studied, the peak strainep was modelled as a function of the Zener–Hollomon parameter and the austenite grain size.