Two bacterial strains, Fuji 18-1(T) and Fuji 23-1(T), were isolated from the blood of the small Japanese field mouse (Apodemus argenteus) and the large Japanese field mouse (Apodemus speciosus), respectively, specimens of which were captured in the forest of Mount Fuji, Japan. Phenotypic characterization (growth conditions, incubation periods, biochemical properties and cell morphologies), DNA G+C contents (40.1 mol% for strain Fuji 18-1(T) and 40.4 mol% for strain Fuji 23-1(T)) and sequence analyses of the 16S rRNA genes indicated that both strains were members of the genus Bartonella. Using rpoB and gltA sequencing analysis, the highest sequence similarities between strains Fuji 18-1(T), Fuji 23-1(T) and other recognized species of the genus Bartonella showed values considerably lower than 91.4 % and 89.9 % in the rpoB gene and 89.1 % and 90.4 % in the gltA gene, respectively. It is known that similarities of 95.4 % for the rpoB gene and 96.0 % for the gltA gene can be applied as cut-off values for the designation of novel species of the genus Bartonella. In a phylogenetic tree based on the merged set of concatenated sequences of seven loci [16S rRNA, ftsZ, gltA, groEL, ribC and rpoB genes and the intergenic spacer region (ITS)], strains Fuji 18-1(T) and Fuji 23-1(T) formed a distinct clade from other recognized species of the genus Bartonella. These data support the classification of strains Fuji 18-1(T) and Fuji 23-1(T) as novel species of the genus Bartonella. The names Bartonella japonica sp. nov. and Bartonella silvatica sp. nov. are proposed for these novel species. The type strains of Bartonella japonica sp. nov. and Bartonella silvatica sp. nov. are Fuji 18-1(T) (=JCM 15567(T)=CIP 109861(T)) and Fuji 23-1(T) (=JCM 15566(T)=CIP 109862(T)), respectively.