Six crossbred male pigs (40 kg) with cecal cannulas were randomly allotted to three treatments for evaluation of the effect of three levels of dietary Solka-floc (2, 10 and 18%) on cecal functionality. Samples were collected every fourth day for 40 days. Blood was obtained 4 hr after the morning feeding, and cecal contents were sampled at 3-hr intervals during the 12-hr period between the morning and evening meals. Blood urea nitrogen was not affected by dietary cellulose, and it remained constant throughout the experiment. Dry matter and cellulose digestibilities were reduced (P < .05) by the increase in dietary cellulose, suggesting a maximum cellulose digestion capability of about 35 g/pig daily. A definite daily pattern was observed for cecal ammonia nitrogen. It reached a maximum 6 hr after feeding. Cecal volatile fatty acid (VFA) concentrations were not affected by dietary cellulose. After 40 days, 150 mg/kg body weight of neomycin sulfate was administered daily for 8 days, 100 mg in the feed and 50 mg into the cecum via the cannula. The antibiotic resulted in a decrease (P < .01) in cecal VFA concentrations, an increase (P < .01) in cecal ammonia N level and a complete arrest of cellulose digestion.