Previously, it was generally believed that the quality of maize is more stable than that of temperate cereals such as wheat and barley and that little improvement in maize quality can be achieved by supplementation with microbial enzymes. More recent research has shown wide variability in the quality of maize from different sources and improvement in its nutritive value when microbial enzymes are included in the diet (Cowieson et al., 2008). The aim of this study was to evaluate the response of broiler chickens to increasing levels of maize with or without dietary supplementation with a microbial enzyme.