Five fusion experiments were conducted with spleen cells from Balb/c mice immunized with purified 146S antigen of foot and mouth disease virus type 'C' (vaccine strain). Monoclones (31) thus developed were isotyped as IgM (3), IgG1 (6), IgG2a (5), IgG2b (3) and IgG3 (14). Eleven clones isotyped as IgM, IgG2a and IgG2b showed neutralizing activity in virus neutralization and plaque reduction tests. Six of the neutralizing clones precipitated 146S virus in Ouchterlony reaction. On the basis of location of MAb reactive epitopes in relation to intact virus (146S), 12S particles and VP1 in ELISA test, the clones were classified as Class II (6), Class III (11) and Class IV (14). These clones may be useful for purposes of antigen detection from field isolates and for estimation of antibody titres in vaccinated animals.