We investigated the genotypes of Leptospira spp. detected in symptomatic dogs in Thailand. During April to December 2012, 6 out of 41 client-owned dogs were diagnosed with leptospirosis based on polymerase chain reaction tests. All of the infected dogs showed clinical symptoms related to leptospirosis. Direct genotyping of the causative agent of the canine leptospirosis was conducted from the archival DNA samples extracted from urine or blood of those 6 infected dogs. Sequencing of the partial 16S rRNA and lipL32 genes from all samples identified Leptospira (L.) interrogans as the infecting species. Multilocus sequence typing tests were successful for 2 out of 6 samples. The sequence type (ST) was identified as ST50 for both samples where the profile corresponded to L. interrogans species and Bataviae serogroup. The presence of this genotype of Leptospira has never been reported in Thailand. Thus, our findings showed the existence of ST50 L. interrogans serogroup Bataviae and the ability to cause leptospirosis in dogs in Thailand.