The antigenic relationships between three similar parvoviruses, canine parvovirus type 2 (CPV), feline panleukopenia virus (FPV) and mink enteritis virus (MEV) were investigated. Antisera against all 3 viruses and monoclonal antibodies (mAb) to CPV were prepared and the viruses compared using several serological methods. When conventional sera were used in the hemagglutination-inhibition and agar gel precipitin (AGP) tests there were no differences between the CPV viral isolates studied, but antigenic differences were revealed between the CPV isolates and the FPV or MEV. Of 16 mAb produced against CPV, six reacted only with the CPV. The other 10 mAb reacted with all three parvoviruses. Additionally, an antigenic difference was detected by AGP tests between one FPV isolate and the other FPV and MEV isolates. Including both conventional sera and mAb to CPV in a single AGP test with the CPV, MEV and FPV antigens permitted the comparison of results obtained with the different antibodies. The results reported revealed antigenic differences between CPV and FPV or MEV that were most clearly defined using mAb.