The aim of this paper is to examine the relationship between reserved seats for ethnic groups in national legislatures and corruption. In 2008, over 30 countries were reserving seats for ethnic groups in their national legislature. The share of seats that was reserved ranged from a 2 percent reserved seats arrangement for a small ethnic minority, to a 100 percent reserved seats power-sharing arrangement between two or more ethnic groups. By applying theories of informal power, this essay hypothesizes that reserving seats reduces corruption. In contrast to the theory, an initial bivariate regression shows that reserved seats are associated with higher levels of corruption. However, when controlling for conflict history, democracy, ethnic fractionalization, GDP/capita, fuel exports, newspaper circulation, and region, this association turns into a negative one, indicating that reserved seats might reduce corruption. The main finding of the study is that having less than 25 percent of the total amount of legislative seats reserved for ethnic groups reduces corruption more than having no reserved seats at all or more than 25 percent reserved seats. This suggests that certain types of reserved seats arrangements are useful for fighting corruption.