Abstract: To investigate the DNA typing of Trichophyton mentagrophytes,and to find the relationship of DNA type with morphology,teleomorph type,the geographic origin and the sites of infection. DNA extraction was carried out by using benzyl chloride and random amplification of polymorphic DNA (RAPD)assay was employed for DNA typing of 42 strains of T.mentagrophytes isolated from clinical specimens and some other dermatophytes,also 8 preserved strains of Arthroderma.Results:(1)Forty two isolates of T.mentagrophytes can be classified into 3 main types,and the intratype polymorphism has been revealed with some primers.(2)There is no simple relationship between DNA type and morphology,but the DNA types are closely related to the geographic origin,and the isolates from different sites of infection have their own genotype characteristics.(3)DNA patterns of Arthroderma benhamiae and A.vanbreuseghemii are distinctly different,while 42 clinical isolates of T.rnentagrophytes share similar pattern with A.vanbreuseghemii.The clinical isolates of T.mentagrophytes can be divided into 3 types by RAPD,and its DNA type has certain relationship with morphology,teleomorph type,the geographic origin and ttie sites of infection.RAPD provides an useful tool for the pathogenic diagnosis and epidemiology study to investigate the source of infection,and geographic distribution of strains.

Key words: Trichophyton mentagrophytes, DNA typing, Random amplification of polymorphie DNA