Fourteen neutralizing monoclonal antibodies (N-MoAbs) were prepared against the F4 strain of feline calicivirus (FCV), the prototype strain of FCV in Japan, and examined for their ability to neutralize FCV isolates. Neutralization-resistant variants of the F4 strain were selected under the presence of 4 individual N-MoAbs in cell culture systems and used in cross-neutralization tests and enzyme-linked immunosorbent assay with all of the 14 N-MoAbs. The results revealed the identification of at least two antigenic determinants on FCV F4: one being more broadly conserved among FCV isolates than the other. Usefulness of antigenic variants resistant to N-MoAbs for analysis of neutralization determinants on FCV was also demonstrated.