Monoclonal antibody reagents that recognize the SARS-coronavirus (SARS-HCoV) are needed urgently. In this report we describe the development and immunochemical characterisation of mAbs against the SARS-HCoV based upon their specificity, binding requirements, and biological activity. Initial screening by ELISA, using highly purified virus as the coating antigen, resulted in the selection of seventeen mAbs. Five mAbs exhibited Western immunoblot reactivity with the denatured spike protein, of which two demonstrated the ability to neutralize SARS-HCoV in vitro. Another four Western immunoblot-negative mAbs also neutralize the virus. These antibodies will be useful for the development of diagnostic tests, pathogenicity and vaccine studies.