To investigate the change pattern of some inflammatory cytokines in brain tissue at the acute phase after brain irradiated. The whole brain of SD rats was irradiated by the single dose of 2, 15, or 30Gy of 4 MeV electron beam. The enzyme−linked immunosorbent assay (ELISA) was used for the measurement of IL−1 β, IL−6, and TNF−α content in hippocampus tissue of rats at 1h, 6h, 12h, 1d, 2 and 1week post−irradiation. The mRNA of IL−1 β, IL−6, and TNF−α were detected by reverse−transcription polymerase chain reaction (RT−PCR) in the same experimental groups. It was analyzed about the influence of dosage and post−irradiation duration with the cytokines expression. Compared with both the normal control and the anaesthetized with chloral hydrate but sham−irradiation groups, there were no difference about the three inflammatory cytokines expression in rats with 2Gy irradiated. At 6h after irradiation with 15Gy, 6 and 12h with 30Gy groups, the content of IL−1 β and TNF−α in hippocampus tissue were significantly increased, and were returned to normal level after 12 to 24h. The same change tendency of their mRNA relational level was observed in 15 and 30Gy groups, but it happened earlier in 1h after exposure. Although the content of IL−6 in hippocampus kept stable in all the groups, its mRNA level raised obviously in 12h group. After 15—30Gy whole−brain irradiation, the expression of some inflammatory cytokines increased abruptly in the hippocampus of SD rat within 1 day, but the interplay between inflammatory cytokines changes and the pathogenesis of radiation injury was incompletely understood at present.