The effects of graded levels of Saccharomyces cerviciae (SC) on performance, carcass characteristic and internal organs size of broilers were investigated in a seven weeks trial using 160 days old Cab 500 mal broiler chicks fed corn-soybean meal based diet. In a completely randomized design 160 chicks distributed to four dietary treatments. Thus each dietary treatment had 4 replication with 10 birds each. Four dietary treatment according to the Saccharomyces cervicia (SC) levels were S (0), S1 (100), S2 (300) and S3 (500 g kg(-1) diet). Each three levels of SC significantly (p < 0.05) affected the Feed Conversion Rate (FCR), during 7-21 days and S3 showed the best FCR but during 21-42 days the S1 was the best (p < 0.05). There was no significance differences in body weight gain (BW) and Feed Intake (FI) between the treatments. SC supplementation did not significantly (p > 0.05) affect Dressing Yield (DY) but dressing yield in SC containing treatments numerically were higher than control. Inclusion and levels of SC significantly (p < 0.05) affected, liver, spleen and Abdominal Fat (AF) weight. As the level of SC in diets increased the liver and spleen weight increased too. But abdominal fat decreased. Supplementation of SC significantly (p < 0.05) affected the intestinal (Large and Small) length (LI, SI), the shortest intestine measured on S3 receiving diet, while the highest intestine measured on bird receiving the control diet. The results demonstrated that compared to control diet supplemental SC significantly (p < 0.05) improve FCR, decrease abdominal fat, intestine length and apparently increase body weight gain, dressing yield, liver and spleen weights and 100 g kg(-1) SC diet give the best.