Abstract: Objective To analyze HIV immunological and serological changes in HIV21 infected individuals and investigate their role.Methods Antibodies,absorptency A value and T cell subsets from 61 HIV infected individuals and 56 AIDS patients were detected by western blot test,FCM and ELISA respectively.Results HIV infected individuals and AIDS patients in different stages of infection had different CD₄⁺ cell(P<0.0001)、CD₄⁺/CD₈⁺ (P<0.0001).Correlation analysis revealed a linear positive correlation between CD₄⁺ and CD₈⁺ (P=0.0051,r=0.369)in 56 AIDS patients.CD₄⁺ and CD₈⁺(P=0.239,r=0.153)had a negtive correlation in HIV infected individuals.Conclusion These results suggest that immunological and serological conditions of HIV21 infected individuals in different stages of infection were significantly different,so they can provided data for clinical stages and disease prognoses and treatment.