Raw, heat treated soybean meal and diets made from soybeans extruded at varying temperature were compared to examine dietary threshold levels of the major soybean antinutritional factors (ANF)for broilers.Whole full-fat soybeans were extruded at 90,100,110,120,130,or 140 C. An in vivo nutritional evaluation of the extruded soybean meals was carried out using 224 Arbor Acres broilers allotted to seven treatments with four replicates of eight birds per pen. As extrusion cooking temperature increased,the urease activity,TI activity,lectin content and PDI decreased. Extruding at 120 C reduced the urease actvity to 0.11 units.the TI activity to 7.20 mg@ g-1 ,and lectin content to zero. Raw soybean meal significantly depressed the growth rate of broiler chickens. Remaining ANF obviously reduced feed intake and dietary nitrogen metabolism. The performance of broilers was improved as extrusion temperature increased. Extruding at 110 C produced an effect equal to that of conventional soybean meal. The weight of the pancreas of the birds fed the raw soybean or 90C-extruded soybean were significantly higher than those in heated-soybean meal group and in the higher temperature-extruded soyean groups. The same tendency was found from 3 to 7 wk of age. The weights of duodenum and ileum of the broilers fed the raw soybean were significantly higher than those in heated-soybean meal group. Extending the feeding of raw soybean or low temperature-extruded soybean to 7-wk-old hroilers significantly increased the fresh weights of proventriculus,jejunum and ileum and dry weights of jejunum and ileum. The villi of birds fed raw soybean meal and low-temperature-extruded soybean meals were shot tened and damaged. Broilers grew well on the diets containing soybean trypsin inhitory activity as high as 3.74 mg @ g-1 without showing any negative effect on the weights of organs and alimentary tracts.