An empirical model is presented to describe the development of the biaxial alignment in ion beam assisted deposited (IBAD) yttria stabilized zirconia (YSZ) films. The model is based on Bradley's description for the orientation of grains on the surface of the IBAD YSZ film. The measured biaxial alignment of the grains on the surface of the YSZ film was plotted as a function of film thickness. The graph was fitted using the equation in our model and the parameters were calculated. We used these parameters to calculate the average biaxial alignment of the YSZ film as a function of thickness. The calculated results are close to the experimental results. (C) 2003 Elsevier Science B.V. All rights reserved.