This study was to investigate the effect of lipoxygenase on the mechanical development of wheat flour doughs. The flour mixtures used for experiments were 100% wheat flour $(S_1)$, 90% wheat flour and 10% raw soy flour $(S_2)$, 90% wheat flour and 10% toasted soy flour $(S_3)$, and 90% wheat flour and 10% toasted soy flour with the addition of lipoxygenase preparation $(S_4)$. When flour mixtures were compared with control $(S_1)$, $S_2$ demonstrated lower water absorption, lower mixing talerance index (MTI) and lower dough weakening and increased dough development time, whereas $S_3$ showed higher water absorption, lower MTI, lower dough weakening and the same dough development time. The addition of lipoxygenase to $S_3$ $(S_4)$ resulted in the same water absorption, longer dough development time, lower MTI and love dough weakening than those of $S_3$, which were comparable with $S_2$. Percent water absorption of flours, obtained from extensograph, was highest in $S_3$ and lowest in $S_2$. Addition of both raw and toasted soy flour to wheat flour resulted in an increased energy, $S_4$ demonstrated higher extensibility and lower resistance to extension than $S_3$, and those values of $S_4$ were comparable with $S_2$. The experimental data obtained from this study suggested that soy flour mixtures containing lipoxygenase had better mechanical dough properties than toasted soy flour mixture without lipoxygenase.