Canine parvovirus (CPV) is a recently recognized pathogen of dogs that is similar to the long-recognized feline, mink, and raccoon parvoviruses. Relationships between the viruses determined from DNA sequences of the capsid protein genes of 10 virus isolates showed the CPV isolates to be closely related to the other viruses, although comprising a distinct group. No immediate ancestor of CPV was observed amongst the mink, cat, or raccoon viruses examined. Three different directly repeated sequences were present within the noncoding region downstream from the capsid protein genes. Analysis of recombinants between CPV and feline panleukopenia virus at restriction sites within the capsid protein genes mapped a CPV-specific neutralization epitope on the virus capsid, differences in the pH dependence of hemagglutination, and part of the determinant of canine host range between 59 and 64 genome map units (m.u.). Those differences were therefore the result of up to three nucleotide or predicted amino acid sequence differences in that region. A second region between 64 and 73 m.u., which may affect the viability of certain recombinant viruses, contained four nucleotide differences, one of which was a coding change.