In this study, we selected only serologically identified 15 Leptosira interrogans isolates in the past and analyzed and identified them by using molecular method. The partial 16S rDNA and LipL32 genes were amplified from the bacteria by polymerase chain reaction (PCR) and sequenced. Sizes of the PCR products were 529 bp and 819 bp respectively and analysis of the nucleotide sequence of 16S rDNA and LipL32 genes showed that 14 out the 15 Leptospira showed 99.4~100% and 99.2~99.9% similarity respectively to those of L. interrogans lai and one isolate named HS-7 showed 100% and 100% similarity to L. interrogans canicola. The phylogenetic tree based on the 16S rDNA and LipL32 genes obtained the study revealed that 14 of the Leptospira composed a cluster distinct to that of L. interrogans lai and HS-7 composed to L. interrogans canicola.