A five-week-long experiment was performed on 960 one-day-old Cobb 500 cockerels divided randomly into ten experimental groups of 12 cages (replicates) of 8 birds each. The objective of the experiment was to estimate the effect of non-starch polysaccharides (NSP) derived from various cereals and addition of microbial enzyme preparations on growth performance, ileal viscosity, liver weight and concentration of short-chain fatty acids in broiler chicken caeca. Barley and oats, hulless barley, naked oats, and rye constituted the majority of diets. Diets were non-supplemented or supplemented with a commercial enzyme preparation. Enzyme preparations significantly improved feed conversion ratio and body weight gains (P<0.05) only in groups fed diets based on naked oats and rye. In all groups, enzyme supplementation decreased intestinal viscosity and increased the concentration of acetate and total short-chain fatty acids in caecal digesta with the exception of the group fed the diet with naked oats. The results indicate that not total dietary fibre content, but the type of dietary NSP, as well as microbial enzyme supplementation, may influence the intestinal viscosity and performance of broiler chickens.