Using the most recent available data on a sample of 40 developing countries, this paper addresses the effects of oil rent on inequality. Mobilizing a dynamic panel data specification over the period 1996–2008, the econometric results yield two important findings. First, there is a non-linear (U-shaped) relationship between oil rent and inequality. Specifically, oil rent lowers inequality in the short run. This effect then diminishes over time as the oil revenues increase. Our complementary finding is that the fall in income inequality as a result of the increase in the oil rent is fully absorbed by the increase in corruption. Further, the paper examines the channels of causality underlying this relationship. The graphical analysis shows the consistency of the data with the hypothesis according to which corruption, military expenditure, and inflation mediate the effect of oil rent on income inequality.