Objective To investigate the variation of T lymphocyte subsets in peripheral blood of the patients with tumor and their clinical significance.Methods The T lymphocyte subsets in peripheral blood from patients with tumor n = 27 and healthy controls n = 25 were detected with flow cytometry.Results The CD3+ T cells,CD4+ T cells and CD4+/CD8+ ratio in patients with tumor were significantly lower than that in the control group.Comparied with the control group the CD8+ T cells in patients with tumor were significantly higher P 0.01 .Conclusion The immunological function of patients with tumor was decreased.The flow cytometry is a rapid,sensitive and accurate measure to detect the immunological function of patients with tumor.It can play an important role in evaluating the curative effect and prognosis of the disease.