In this study, effects of dopants including Bi2O3, Ta2O5, Sb2O3 on sintering and microstructure development in ZnO-based electroceramics were investigated. Bi2O3 addition to ZnO enhances the densification process and results in abnormal grain growth. Addition of Sb2O3 to the ZnO-Bi2O3 (ZB) system retards the densification process and inhibits the grain growth. Although addition of 0.05 mol% Ta2O5 seems to have almost no effect on sintering of the ZB system, it induces anisotropic grain growth in the ZB system. Although 0.05 mol% Ta2O5 addition to the ZS system shows no effect on the densification, the 0.1 mol% Ta2O5 added system exhibits retarded densification behavior. This is attributed to a critical concentration above which Ta2O5 inhibits the densification in ZnO-based electroceramics.