Abstract: A preliminary identification of small egg white peptides at different incubation period were established by sodium salt(sds)-polyacrylamide gel electrophoresis(SDS-PAGE)and matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF MS/MS). The results showed that 837,879,872 and 842 peptides were identified at 0,6,14 and 16 d of incubation,respectively(a total of 3430). Except clusterin peptides of other high abundance proteins in egg white were not detected. 926 peptides were derived from nine proteins related to innate immunity of chicken embryos,such as ovodefensin,interleukin-6. 256 peptides were derived from three proteins related to the development of chick embryonic respiratory system(cx9C motif-containing protein,sprout protein and carbonic anhydrase). These natural peptides might play an important role in the respiratory and immune systems formed during chick embryo development. The results further emphasized the bioactive action of egg white-derived peptides as related to chicken embryonic development,and the potential use of these molecules as additive ingredients in the preparation of functionalfoods.