Abstract The post-1991 Ethiopia has introduced multi-party system, although the practicability of genuine multi-party democracy is remained debatable. Political party pluralism is believed to be an important political system to widen the political choices of the public. But, this can be realized if the political parties in the pluralistic party system have feasible policy alternatives. The mere propagation of political parties without having feasible policy alternatives could not be a guarantee for democratization and state transformation. Especially, the proliferation of ethnicbased political parties along extremely divergent political agendas and interests more contaminated the state politics since it is difficult to attain consensus at a political condition where there are extensive and irreconcilable political issues and interests. Thus, the main aim of this study was to examine the implications of ethnic-based political parties’ proliferation on the national consensus of post-1991 Ethiopia. To achieve the main objective of this study, qualitative research approach was employed; and the data were collected both from primary and secondary sources. Semi-structured interview was employed as data collection instrument while primary data were collected, and the secondary data were collected from various written documents. The collected data both from primary and secondary sources were analyzed through the use of thematic analysis. The finding of the study shown that, the proliferation of ethnic-based political parties with irreconcilable interests and contradictory political agendas in post-1991 Ethiopia is resulted by the intensification of clash of interests, the aggravation of ethnic political elites’ rivalry, escalation of ethnic mistrust, deterioration of national sentiment and widening of disagreements on the issues of national symbols and national identity issues. Accordingly, the major conclusion of this study revealed as the proliferation of ethnic-based political parties’ is a threat for national consensus in post-1991 Ethiopia. Key Terms: Ethnic-based party, party proliferation, party system, national symbol, national consensus