Two experiments were conducted with broiler-type chicks 1) to compare the bioavailable amino acid values of corn, sorghum, soybean meal and fish meal as measured by two different bioassays including total fecal collection (TFC) method of Bragg et al. (1969) and true metabolizable energy (TME) assay of Sibbald (1976), and 2) to predict the accurate bioavailable amino acid values of the test materials by a feeding trial. For apparent amino acid availability (AAAA), the results obtained from TFC group showed insignificant differences among the test ingredients. In TME group, however, the AAAA values of the carbohydraterich feedstuffs including corn and sorghum were significantly (P$lt;0.01) lower than those of protein-rich feedstuffs including soybean meal and fish meal. Between the two bioassays, the average AAAA values of the test feestuffs were significantly (P$lt;0.01) higher in TFC groups. Unlike the AAAA values, the average true amino acid availability (TAAA) values among feedstuffs were not significantly different in both TFC and TME groups. Between the two bioassays, however, the average: TAAA values of the test feedstuffs were slightly higher, but not significantly different, in THE than in TFC groups. Body weight gain and feed efficiency were slightly improved when the diets were formulated by the availability data rather than chemical contents of corn and soybean meal. Between TFC and TME groups, there were no differences in the growing performance of broiler chicks. Therefore it was impossible to say that which assay was under of overestimated the amino acid bioavailability values of the feedstuffs.