This paper analyzes the adoption and impacts of improved maize varieties (IMVs) on food security in Ethiopia. Survey data collected in 2011 from 2455 sample households in 39 districts was used in the analysis. Endogenous switching regression model supported by binary and generalized propensity score matching methods was used to empirically assess the impact of IMV adoption on per-capita food consumption expenditure and perceived household food security status. Results show that education of household head, farm size, social network, and better agro-ecologic potential for maize production are the major determinants of household decisions to adopt IMVs. In addition, the average per-capita food consumption is high for adopters and the impact of IMV adoption on per-capita food consumption is slightly higher for non-adopters had they adopted IMVs. Thus, policies and development strategies encouraging further adoption of IMVs could enhance food security of smallholder farmers in maize-based systems.