目的　了解恙虫病东方体 Ｃ Ｍ Ｙ 株与其它株的关系。方法　测定 Ｃ Ｍ Ｙ 株 ｓｔａ５６ 基因片段的核苷酸序列并与其它株相应序列进行比较。结果　在测定的３２４ｂｐ 序列中， Ｇ Ｃ 含量为４３５ ％ ； 与 Ｋａｒｐ 、 Ｇｉｌｌｉａｍ 、 Ｋａｔｏ 、ｋｕｒｏｋｉ、 Ｋａｗａｓａｋｉ 及 Ｓｈｉｍｏｋｏｓｈｉ 株相应序列的同源性分别为９１０ ％ 、８７３ ％ 、８７０ ％ 、８７３ ％ 、８６１ ％ 及７３８ ％ 。结论　 Ｃ Ｍ Ｙ 株与已报道的恙虫病东方体菌株不同， 与 Ｋａｒｐ 株有很高的同源性。 OBJECTIVE To understand the relationship between C M Y strain of tsutsugamushi disease and other strains. Methods The nucleotide sequence of sta56 gene of C M Y strain was determined and compared with the corresponding sequences of other strains. Results The Gc content was 435% in the 324 bp sequence. The homologies with the corresponding sequences of Karp, Gilliam, Kato, kuroki, Kawasaki and Shimokoshi strains were 910%, 873%, 87 0%, 873%, 861% and 738%. Conclusion The C M Y strain is different from the reported Ostracoda tsutsugamushi strain and has high homology with Karp strain.