Theoretical γ-values calculated from crystallite orientation distribution functions by using the Taylor theory have been compared with experimentally measured γ-values in annealed aluminum alloy sheets. The calculated and measured γ-values for a 6061 aluminum alloy consisting of the retained rolling texture and of the cube texture are relatively well consistent, but these values for a 5052 aluminum alloy consisting mainly of the cube texture are less consistent in the vicinity of a 45° direction. This is thought to be essentially due to the lack of validity of an analytical model for the 5052 alloy. Planar anisotropy of the γ-value, however, can be generally estimated by the present model. From the calculated results concerning some ideal orientations, it is found that a high γ-value may be obtained by developing the R-orientation as a main component and the Goss orientation as a secondary component.