In our previous studies, we have infected Rhesus monkeys and Cynomolgus monkeys with SARS-CoV as the SARS model, and also, We have developed the inactivated vaccine to vaccinate Rhesus monkeys to protect them from SARS-CoV challenge. However, we wonder that the infected monkeys whether could or not be re-infected, and the acquired neutralization antibodies whether could or not play a role to protect the monkeys from SARS-CoV infection. In this study, we used four groups of monkeys, from which, the group 1 had three recovered Rhesus monkeys from SARS-CoV infection for 1 year; the group 2 had three recovered Cynomolgus monkeys from SARS-CoV infection for 1 year; the group 3 had three Rhesus monkeys that were transfused 10 ml of serum with high titer of neutralization antibody against SARS-CoV after 2 days of virus inoculation; and the group 4 had two Rhesus monkeys for SARS infecting control. the SARS-CoV strains PUMC01 isolated from patients in Beijing was used for infection.From the results of RT-PCR test, virus isolation, neutralizing antibody test, pathological examination and other lab tests and comparing with the data from SARS monkeys, we concluded that the monkeys recovered from SARS in group1 and group 2 showed strong protection from SARS-CoV challenge, the SARS-serum-transfused monkeys showed week protection from SARS-CoV challeng.