Abstract: The objective of this experiment was to research the effects of injection recombinant chicken interferonγ (rChIFNγ) in the prophase on immunological stress broilers. Forty 14dayold healthy AA broilers were allotted to 4 groups randomly which were group A, group B, group C and group D. The broilers of group A and group B were injected with 1 mL PBS at 14, 21, 28 and 35 days of age. At the same time, the group C was injected with 50 μg rChIFNγ (in 1 mL PBS) and the group D was injected with 100 μg rChIFNγ (in 1 mL PBS). At the time of 36dayold, 38dayold and 40dayold, the broilers of group B, group C, group D were injected with PBS (1 mL) which contained LPS (250 μg·kg-1 BW). At the same time, the broilers of group A were injected with PBS (1 mL) only. The performance indices were recorded at the time of 36dayold. Recorded the weight and intake of each broilers from 36 to 41 days. Hematologic indices and Tlymphocytes proliferation of broilers were assayed at 12 hours post the third injection of LPS. The concentration of interleukin 1 (IL1) and corticosterone (CORT) in the serum were measured at 12, 24, 36 hours post the third injection of LPS. The results showed that: (1) during the challenge, the growth performance was not affected by rChIFNγ (P>0.05); (2) 12 hours after the third injection of LPS, the white blood cell counts of group C and group D were higher than that of group A (P<0.05) and group B (P<0.05); (3) 12 hours after the third injection of LPS, the Tlymphocyte stimulation index of group C and group D were higher than that of group A and group B (P<0.05); (4) 12 hours after the third injection of LPS, the CORT of group A was lower than that of group B (P<0.05); 24 hours after the third injection of LPS, the CORT of group A was lower than that of group B (P<0.01), group C (P<0.05) and group D (P<0.05), 36 hours after the third injection of LPS, the CORT of group A was lower than that of group B (P<0.05); (5) 12 hours after the third injection of LPS, the IL1 of group A was lower than that of group B (P<0.05), 24 hours after the third injection of LPS, the group A was lower than that of the other groups (P<0.01). As the results shown, injection of rChIFNγ at prophase could release the IL1 and CORT in the immunological stress broilers, improve the cell immunity during the stress.