Logs of hot strip mill processing of Ti-Nb IF steels were examined so that the mean flow stresses at each pass were calculated. The computation of the mean flow stress was carried out using the Sims-equation and taking into account the forward slip ratio, the redundant strain and the work roll flattening. The mean flow stresses are compared to predicted values obtained from a model. As strip rolling is carried out with decreasing pass interval and increasing strain rates, the interpass times ranges from two to four seconds between the first and the second stands to a few tenths of a second between the last two stands. The present model takes into account the occurrence of softening by dynamic recrystallization. The predictions of the mean flow stresses during rolling obtained from the simulations are in good agreement with the data set obtained from the logs.