Disclosed herein are monoclonal antibodies (Mabs) against ricin toxin and its subunits. The Mabs were initially selected based upon their ability to bind to ricin and its individual subunits in a solid-phase enzyme-linked immunoassay (ELISA). Several candidates were selected for further evaluation, including their ability to inhibit ricin intoxication in vitro and for their utility as immunodiagnostic reagents. As disclosed herein, the Mabs may be used in immunoassays. Also disclosed, are use of the Mabs to inhibit ricin-mediated eukaryotic cell cytotoxicity in vitro, thereby indicating that these Mabs may be used to prevent and treat ricin intoxication in vivo. Kits comprising the Mabs are also disclosed.