The influence of the difference in initial tooth flank form of hypoid gears on the progress of tooth flank wear and its influence on gear performance is discussed. The tooth flank forms of two new gears from the same production line as that of wear tested gears were employed as the initial state. The wear simulation developed by this investigation has revealed that the tooth of pinion is prone to considerable wear, and when the tooth flank wear develops itself enough, the composite error surface of worn gears tends to have a resemble 3D figure. The change of the gear performance with progress of tooth flank wear is although somewhat different as function of the difference in the initial composite error form of individual gears. The difference in the change of vibrational excitation with progress of tooth flank wear is especially large. The maximum value of static stresses generally decrease in some extent with progress of tooth flank wear so long as wear is not severe enough.