Broiler chicks were fed a corn-soybean meal diet or a corn-soybean meal diet containing either 15% rice bran, 15% wheat bran, 15% alfalfa meal, 10% cellulose, or 10% cottonseed hulls. All diets contained 3190 kcal/kg of metabolizable energy, 22.8% protein, and either 1.0% calcium and .5% nonphytate phosphorus (Pnp) or .85% calcium and .42% Pnp. The diets were fed for 3 weeks at which time a digestion trial was conducted to determine the amount of phytate hydrolyzed. Chicks consuming diets containing the lower levels of calcium and Pnp hydrolyzed more phytate than those fed the higher levels of calcium and Pnp except when the diet contained rice bran. Less phytate was hydrolyzed in the rice bran diet at the lower calcium and Pnp levels. Phytate hydrolysis was not affected by wheat bran but was reduced by cottonseed hulls. At the lower levels of calcium and Pnp, alfalfa meal and cellulose significantly increased phytate hydrolysis by chicks. The hydrolysis of phytate was influenced more by calcium and by source than by fiber or by level of phytate fed.