Abstract: Objective To investigate the DNA polymorphism of saprophytes and pathogenicity of Cladosporium species and to find out the relationship between them.Methods The total DNA was extracted with benzyl bromide.Random amplification of polymorphic DNA(RAPD) assay was used to study the finger printing of 26 strains from 16 species.Results Of ten random primers used,two (primer 2,5) gave good reaction.The sequences of them were:primer 2:5'-AGCGTCCTCC-3',primer 5:5'-CAGCACCCAC-3'.There were some degrees of variation in RAPD patterns of 26 isolates,with interspecies and intraspecies variation.Genetic similarity of 26 strains was about 37.4%.The isolates of the same species showed high genetic similarities.Some saprophytes located in the same group of dendrogram of Cladosporium species with humanpathogenicity.Conclusion There are some genetic similarities between different species and strains,but no distinct characteristics are found between saprophytes and humanpathogens.

Key words: Cladosporium, Random amplified polymorphic DNA te chnique