OBJECTIVE: To study the level and significance of T helper 17 (Th17) and CD4(+) CD25(+) regulatory T cells (Treg) in peripheral blood of patients with sepsis and to evaluate the effects of Xuebijing injection on them. METHODS: ¹ Sixty-four patients with sepsis in intensive care unit (ICU) of Anhui Provincial Hospital were divided into three groups: sepsis group (n=26), severe sepsis group (n=21), and septic shock group (n=17). Eighteen healthy individuals served as controls. The comparison in the expression of Th17 and CD4(+)CD25(+) Treg within groups and the correlation between their levels and the severity of sepsis was made. ² Sixty-four patients were also randomly divided into two groups: routine group (n=25, received routine bundle treatment) and Xuebijing treatment group (n=39, received bundle treatment + Xuebijing treatment). Patients in Xuebijing treated group were given 50 ml Xuebijing injection two times per day in addition to routine bundle treatment. Seven days constituted one course of treatment. The expressions of Th17 and CD4(+) CD25(+) Treg of 64 patients on the 1 day and 7 days after treatment were detected by flow cytometry. The effects of Xuebijing injection on the patients were evaluated. RESULTS: ¹ The expression rate of Th17 and CD4(+)CD25(+) Treg was (0.84 ± 0.29)% and (0.43 ± 0.20)% respectively in control group, and they were lower than that of patients with sepsis (P<0.05). The expression rate of Th17 was higher in severe sepsis group [(3.18 ± 0.84)%] than that of other two groups (P <0.05). Moreover , The expression rate of CD4(+)CD25(+) Treg was highest [(3.28 ± 0.76)%] in septic shock group (P<0.05) , and it was positive correlated with acute physiology and chronic health evaluation II (APACHEII) score and blood lactate (r(1)=0.519, r(2)=0.451, both P =0.01) in all 64 patients. ² Compared with routine group, our study indicated that Xuebijing injection could reduce the abnormal expression of Th17 [(1.72 ± 0.69)% vs. (2.35 ± 0.81)%,P<0.05] and CD4(+)CD25(+) Treg [(1.78 ± 1.00)% vs. (2.30 ± 0.85)%,P<0.05] and decrease length of stay in ICU [(4.7 ± 2.6) days vs. (7.5 ± 4.3) days,P=0.002]. It also lowered 28-day mortality of patients with sepsis, but the difference between two groups was not significant (20.5% vs. 28.0%,P>0.05). CONCLUSION: The expression of Th17 and CD4(+)CD25(+) Treg was increased in sepsis patients and was positively correlated with severity of sepsis, suggesting that they may play an important role in pathogenesis of sepsis. Xuebijing injection could decrease the abnormal expression of Th17 and CD4(+) CD25(+) Treg and tend to decrease the fatality rate of sepsis.