Abstract: Objective To observe the effect of ulinastatin on cell immunity in perioperative esophageal cancer patients. Methods Seventy-two esophageal cancer patients were randomly divided into ulinastatin group(group U) and control group(group C),36 in each group.Patients in group U were intravenously injected with 20ml 0.9% sodium chloride solution containing ulinastatin(2×10⁵ unit)after anesthesia,which was repeated if the operation was longer than 2h.Those in group C were only injected with 20ml 0.9% sodium chloride solution.Blood samples were taken from both groups at 24h before operation(T0),90 minutes in operation(T1),on day 1 after operation(T2),on day 3 after operation(T3),on day 7 after operation(T4).The number of T lymphocyte subgroups(CD3⁺,CD4⁺,CD8⁺,CD4⁺/CD8⁺) and NK cells was calculated by flow cytometry. Results No significant difference was found in the number of T-lymphocyte subgroups and NK cells between the two groups at T0.The number of CD3⁺,CD4⁺,CD4⁺/CD8⁺ and NK cells was significantly lower and that of CD8⁺ was significantly higher at T1,T2,T3 than at T0 in group C(P<0.05 or P<0.01) and returned to the T0 level at T4 except for that of CD8⁺ and CD4⁺/CD8⁺.No significant difference was found in the number of T-lymphocyte subgroups and NK cells in group U at T1.The number of CD3⁺,CD4⁺,CD4⁺/CD8⁺ and NK cells was significantly higher and that of CD8⁺ was significantly lower in group U at T2,T3,T4 than at T0(P<0.05 or P<0.01). Conclusion The cell immunity in perioperative esophageal cancer patient is decreased.Ulinastatin can promote recovery of T-lymphocyte subgroups,thus protecting and improving the cell immunity of such patients.