Canine parvovirus is a newly emerged virus that was first isolated in 1978. As with all new viruses CPV continues to show active evolution, demonstrated by the appearance of new antigenic types. These new types termed CPV-2a and CPV-2b have replaced the original type CPV-2 throughout the world. The reason for the evolutionary advantage of the new viruses was most likely the acquisition of a new host, the cat. The new types are in contrast to CPV-2 able to infect and replicate in cats. Interestingly, about 10 per cent of the parvovirus isolates made from routine diagnostic cat materials were found to be canine parvovirus type 2a or 2b. The relevance of these findings for the epizootiology of parvovirus infection of dogs and cats and also for the vaccination are discussed.