The impact of agricultural market liberalization on maize output in Kenya and Zambia and its effect onfood security in these countries is evaluated in this paper. The findings suggest a weak policy influence onmaize output, but the precipitation and acreage variables stand out as core determinants of maize output.Overall, the obtained results, agricultural markets in general, and the maize sub-sector in particular,responded more positively to implemented policies in Kenya, than in Zambia. Pre-existing economicstructures would have contributed to the outcome. Effective policy implementation would have to betailored to meet regional needs and local conditions. Region and sector dynamics were not consideredwhen formulating and implementing structural adjustment policies in the 1980s. It can be inferred fromthe study that countries with strong economic institutions performed better than those which had weakones.