The invention relates to a monoclonal antibody, or fragments thereof, for isolating and/or identifying mesenchymal stem cells. In this connection, the antibody, or fragments thereof, bind to an antigen which is the same as that bound to by an antibody which is produced by the hybridoma cell line W8B2, which was deposited on 14.08.2002 in the DSMZ [German collection of microorganisms and cell cultures] under the number DSM ACC2567.