Abstract: A limitation in advancing the study of HIV-1 is the lack of a suitable small animal model system that allows for HIV-1 infection to be monitored.A mouse model of AIDS would be very useful because of it practicality and the ready availability of knowledge,reagents and immunogenetics.SCID-hu (Thy/Liv) mouse model,in which human fetal thymus and liver tissue are co-implanted into severe combined immunodeficient mice and resulting in a functional human hematopoietic organ (Thy/Liv),recapitulates the effects of HIV-1 infection in the human thymus.SCID-hu (Thy/Liv) mice are attractive and well-established small animal models for the study of HIV-1 infection in vivo.The humanized SCID mouse model would be served as valuable tools for in vivo studying pathogenesis of HIV,analysis of candidate anti-HIV drugs and vaccines prior to their clinical evaluation in human.