Abstract: Objective CD4⁺CD25⁺Treg cells in peripheral blood were measured in patients with chronic benzene poisoning, the workers occupationally exposed to benzene, and healthy persons without any exposure to benzene, respectively. The clinical significance of CD4⁺CD25⁺Treg cells change in the patients with chronic benzene poisoning was discussed. Methods the peripheral blood samples of 30 patients with chronic benzene poisoning, 30 workers occupationally exposed to benzene and 30 healthy persons were collected. CD4⁺CD25⁺ Treg cells were detected with Fow Cytometry in their mononuclear cells samples. Results The patients with chronic benzene poisoning had lowest CD4⁺CD25⁺ Treg cells level compared with healthy persons or workers occupationally exposed to benzene. However, there was no significant difference between percentages of Treg cells in workers exposed to benzene and that in healthy persons (P>0.05). Conclusion The patients with chronic benzene poisoning had cell immune dysfunction. The decrease of percentage of CD4⁺CD25⁺Treg cells maybe play a role in the occurrence of chronic benzene poisoning,and the CD4⁺CD25⁺ Treg may be used as a biological indexes to monitoring the long-term exposure to benzene.