The objective of this paper is to thoroughly review the theoretical and empirical literature on the impact of economic integration from the perspective of the performance of listed firms in East African. The findings reveal that whereas there are several theories that underpin integration, none can individually explain it. The static and dynamic theories dominate, while the gravitational model remains the most used method. The literature shows that most studies have been done in the developed countries and less in the developing world. The findings reveal a positive association between integration and trade in the developed nations while in the developing world the findings are mixed. Overall there is hardly any literature on the impact of integration at firm level and none for listed firms in EAC. The scanty literature and mixed findings in the developing world indicate a research gap and therefore more research should be carried out