Abstract: Bioremediation is a technique that uses living organisms,micro-organism in particular, to remove pollutants from contaminated environments. Bioremediation has gained momentum in recent years because of its low investment requirement and environmental impact as compared with other remediation techniques and has thus become a viable and promising mode for restoring contaminated sites. In this paper,key factors, including biological factors, nutrient factors, O₂ and electronic receptors, surfactants,co-metabolites, that affect bioremediation are discussed, some successful examples of bioremediation are given, and the merits and demerits of bioremediation expounded.