Abstract: During a survey for possible rickettsial vectors in villages of the central part of the Thai-Myanmar border from September 2001 to February 2002, four species of fleas were collected from common peridomestic animals. All fleas were tested by PCR to detect DNA of bacteria of the genera Rickettsia (gltA and ompB genes) and Bartonella (ITS and ftsZ genes). Sequencing of PCR-amplified products was done using gltA fragments for Rickettsia and ftsZ fragments for Bartonella. Two genotypes related to Rickettsia felis were identified in three Ctenocephalides canis and one C. felis specimen. Further, the following Bartonella spp. were detected: Bartonella henselae in two C. felis specimens; Bartonella clarridgeiae in three C. felis specimens; and a new Bartonella genotype in one Nosopsylla fasciatus specimen. Rickettsia and Bartonella may be frequently detected in fleas infesting peridomestic animals from the western border of Thailand.