The roles of beneficial microorganisms as important inducers in the development and functions of the gastro-intestinal tract of chickens has aptly presented a need for understanding of how these microbes exert health and growth promoting effects on the host chickens. This review focuses on the microbes-host interactions mechanism leading to the proliferation of beneficial microbes and the colonisation of harmful microbes in the gut of chickens. Insight is provided on gut microflora development and control as it influences productivity of chickens. The future role of gut microorganisms and microbial dynamics in poultry nutrition as the basis for optimal utilisation of feed resources and hosts' immune development is highlighted.