The development of through-thickness texture inhomogeneity was systematically investigated in an interstitial free (IF) steel to evaluate its effect on the formability. The through-thickness texture gradient of the final product, i.e. fully annealed steel sheet, depended upon the hot rolling conditions such as slab reheating temperature, rolling schedule and rolling temperature. In order to reflect the effect of through-thickness texture inhomogeneity on the deep drawability, a new parameter R-T was introduced and discussed with the conventional indices, (R) over bar and DeltaR, in terms of formability prediction.