Prevalence of canine parvovirus type 2 (CPV-2) in Japanese dogs and genomic variations among the virus strains were examined. Two-step polymerase chain reaction with double-nested primer pairs designed in the NS and VP1/VP2 genes of CPV-2 was developed for the detection of the viral genome in faecal samples. A total of 74 samples obtained from diarrhoeal house dogs between 1993 and 1995 were tested by the PCR. The virus-positive rate was 54.1%, showing that CPV-2 is still involved in many cases of acute infectious diarrhoea in Japanese dogs. The VP1/VP2 gene of the positive samples was subjected to restriction fragment length polymorphism (RFLP) analysis and nucleotide sequencing. RFLP patterns of the samples were almost identical to those of one CPV-2 strain (TDKet-91-42) isolated in 1991, but different from those of the CPV-2 in the late 1970s and 1980s. The results suggest that a new genotype of CPV-2 appeared and spread among Japanese dogs in the early 1990s.