Two neutralizing human scFv, b1 and h12 were identified initially using ELISA,employing highly purified virus as the coating antigen. The biosensor technique based on imaging ellipsometry was employed directly to detect two neutralizing monoclonal antibodies and serial serum samples from 10 SARS patients and 12 volunteers who had not SARS. Further, the kinetic process of interaction between the antibodies and SARS-CoV was studied using the real-time function of the biosensor. The biosensor is consistent with ELISA that the antibody h12 showed a higher affinity in encountering the virus than antibody b1. The affinity of antibody b1 and antibody h12 was 9.5 x 10(6) M(-1) and 1.36 x 10(7) M(- 1), respectively. As a label free method, the biosensor based on imaging ellipsometry proved to be a more competent mechanism for measuring serum samples from SARS patients and the affinity between these antibodies and the SARS coronavirus.