1. A caecal intubation technique was developed to determine the amount of digesta that enters the caeca of fed and feed-deprived chickens. 2. Dry matter intakes per day for control and caecostomised chickens were not significantly different. 3. For fed and feed-deprived roosters, water intake was significantly increased by caecostomy in control birds and was significantly increased by feeding. 4. Amount of caecal dry matter excretion was significantly increased by feeding, but no difference in caecal water excretion was observed. 5. The ratio of caecal excretion (caecal/total excretion) of dry matter and water tended to decrease in response to feeding. 6. It is concluded that dry matter entry into the caeca represents 18% or 25% of the total dry matter excretion in fed or feed-deprived birds, respectively. Corresponding values for water entry are 17 and 26%. Therefore, the caeca play an important role in water balance.