Abstract: Abstract The main objective of this experiment was to determine the effects of the amount of CP and starch in the diet of steers on ruminal fermentation, passage of starch to the small intestine, and starch digestibility. For this purpose, 4 Holstein steers fistulated in the rumen and abomasum were used in a 4×4 Latin square design at four treatments. With four level of CP and two level of starch in the diet. On an air-dry matter basis, diets contained 25% hay, 25% alfalfa and 50% concentrate. Digestibilities in the rumen and total tract of starch were unaffected by increasing the dietary CP or decreasing the starch of diet (p>0.05), The percentage of starch apparently digested in the rumen and total tract were 83.5% and 97.4%, respectively. Increasing dietary CP or decreasing dietary starch decreased the ruminal outflow, apparent ruminal and total tract digestion of starch (p<0.05). Results of this study suggest that decreased the proportion of starch consumed by the steers that was apparently digested in the small intestine. the amount of starch in the diet of steers on starch passage to the small intestine.