Abstract: Objective To investigate the effect on T-lymphocyte subsets of peripheral blood and serum Interleukin-2 activity in rats exposed to Acrylonitrile for 28 days.Methods　The four posioned groups were given acryloniyrile of 102mg/m³,134mg/m³,178mg/m³,237mg/m³ through respiration.The rats were poisoned for 2 hours every day,at same time not drinking water,they had rest one day after six day posining,totaling 28 days.Results　In the T-lymphocyte subsets profile,positive percentages of CD3,CD4 and CD4/CD8 ratio of peripheral blood were significantly lower in groups exposed to Acrylonitrile than that in normal controls,positive percentages of CD8 of peripheral blood was significanthigher in groups exposed to Acrylonitrile than that in normal controls.The serum Interleukin-2 activity in Acrylonitrile exposing groups was significant lower than that in normal controls.Conclusion　Acrylonitrile can cause impairment to the cellular immune.