We investigate the effects of wage inequality on labor productivity in manufacturing industries. Two particular types of wage inequality are considered: relative deprivation and efficiency wages. Using Taiwanese data from 1979 to 1996 and Korean data from 1993 to 1996, our results indicate that relative deprivation has a highly negative effect on industrial productivity while the effect of efficiency wages is not statistically significant. Although many studies by labor economists have focused on efficiency wages, our findings underscore the importance of relative deprivation. The results also generally consistent with the view that, in order to maintain high productivity, manufacturing firms must be concerned with the social legitimacy of their wage distributions.