AIM: To investigate the immunologic mechanism of CXC chemokine ligand 10(CXCL10) and its receptor CXC chemokine receptor 3 (CXCR3 ) involved in the process of endometriosis (EM). METHODS: Serum samples were collected from 3 groups; EM patients without operation (n = 76) , EM patients with operation (n = 10) and the normal control persons (n =76). CXCL10 and CA12S concentrations were detected by means of ELISA and chemilumino-metry. Cell surface antigens on the activated PBMC - CD3 and CXCR3, as well as CXCR3 subgene - CXCR3A and CX-CR3B were tested by flow cytometry (FC) and RT - PCR when PBMC was separated from women with EM ( n = 10) and without EM (n = 10), and then activated. RESULTS: Serum CXCL10 concentrations between three groups were signifi-canly different (P < 0.05). Compared to normal control group, although the supernatant CXCL10 concentration and CD3~+ /CXCR3~+ PBMC number in EM group has no significant difference (P >0.05) , highly expressed CXCR3B in EM group rather than CXCR3A was observed. CONCLUSION: CXCL10 in women with EM is low, indicating that it plays a vital role in the process of EM and immune system of the women with EM is defected and impaired. The immunoreactivity of PBMC from both EM patients and normal person is same to activated signal, but the productions are different: PBMC in EM group mainly express CXCR3B but PBMC in normal person mainly express CXCR3A after activation, which may be one of the immune mechanisms that EM escapes from immunological lethal effect of the infected host.