Diets based on barley and peas ground to two particle sizes and with one of two diet formulations were fed to cannulated grower pigs. Energy digestibility was effected by particle size but not diet formulation. Total nitrogen excretion was affected by diet formulation, but not partilce size. Reducing particle size from 900 to 600 mm increased total tract and ileal energy digestibility by 3-10%, respectively. Reducing particle size from 900 o 600 mm did not alter urinary or total nitrogen excretion, but reduced fecal nitrogen excretion by 11%, indicating that particle size reduction improved nitrogen digesyibility but did not reduce total nitrogen excretion. Reducing particle size was effective in reducing feacl but not total nitrogen excretion. Diet formulation is more effective in reducing nitrogen excretion.