To identify potential vectors of Lyme disease in China, the polymerase chain reaction (PCR) was used to detect fla-gene DNA of Borrelia burgdorferi in various species of ticks. A 126-bp product defined by the specific primers was detected in all seven geographic strains of B. burgdorferi isolated from Ixodes persulcatus Schulze and Clethrionomys rufocanus Sundevall. When the PCR was applied to tick specimens stored in museum, the minimal positive rate of five pools (138 ticks) of I. persulcatus was 4.3%. Of twelve Ixodes granulatus Supino examined, 25.0% were positive. There was no evidence for B. burgdorferi in other species of ticks.