1. In two experiments, no consistent differences in weight gain or food intake appeared between broiler chickens given diets based on whole or rolled barley, but food: gain ratio and gizzard weight as a percentage of live weight were reduced (P < 0.05) when barley was rolled. Grit addition did not affect performance or intestinal characteristics. 2. In a third experiment, whole barley diets gave significantly higher weight gain than ground barley diets; this was attributable to the significantly higher food consumption. Gizzard weight as a percentage of live weight increased (P < 0.05) when whole barley was fed, while food: gain ratio was not significantly (P > 0.05) affected by the form of barley. 3. The number of particles in the intestinal contents with sizes larger than 2.4 mm was not significantly (P < 0.05) different between broiler chickens fed on whole barley and those fed ground barley, but the number of particles with sizes between 2.4 and 0.7 mm was lower P < 0.05) when diets with whole barley were fed. 4. Enzyme addition increased (P < 0.05) weight gain and the DM of intestinal contents, and decreased (P < 0.05) intestinal viscosity, food: gain ratio and pancreas weight as a percentage of live weight regardless of form of the barley.