This experiment was carried out to investigate the effects of antibiotics(oxytetracycline (OCT), nosiheptide (NH), sulfathiazole(SUL) enzyme(ENZ), yeast culture(YST), probiotics(LBC), and β-agonist(β-AG) on the performance and nutrient availability of broilers. Two hundred eighty eight(♀ 144, ♂ 144) broiler chickens were allotted to pens of 8 treatments. The results obtained are as follows: 1. During the starter period(0 to 21 days), broilem treated with nosiheptide and β-agonist showed lower weight gain than those fed control diets(p$lt;0.05). Fete intake of groups fed β-agonist was less than that of groups fed control diet(p$lt;0.05). Broilers offered nosiheptide tended to have greater weight gain than the control group during Ehe finisher period (21 to 42 days), and feed/gain was 5.6-6.1 % superior to the control. During the entire period (0 to 42 days), nosiheptide, enzyme and β-agonist treatments improved feed/gain by 2.9, 5.3 and 3.4% compared with the control, respectively (p$lt;0.05). 2. OTC, nosiheptide, sulfonamide and enzyme treatments showed higher fat availability than the amtrol at 2 weeks of age. Also, nosiheptide treatment showed higher dry matter and fat availability than the control at 6 weeks of age. Enzyme treatment showed better protein and NFE availability than the control at 6 weeks of age. Supplementation with yeast culture, probiotics and β-agonist showed higher fat availability than control at 2 weeks of age. 3. Residues of OTC and SUL in the broiler muscle were 0.333 ppm and 0.07 ppm, respectively, which was less than the tolerance limits (1.0 ppm and 0.1 ppm) regulated by Korea, U.S.A. or Japan.