DNA fingerprinting and polymorphism among the Chinese drug "Ku-Di-Dan" and its substitutes were demonstrated with arbitrarily primed polymerase chain reaction (AP-PCR) and random amplified polymorphic DNA (RAPD). Distinctive, reproducible genomic fingerprints from DNA of the Chinese drug Ku-Di-Dan and 9 species of Compositae were generated with six long (18-24 mer) and one short (10 mer) random-chosen primers with PCR. Ku-Di-Dan samples can be distinguished according to the banding patterns of their amplified DNA on agarose gels. Results showed that AP-PCR and RAPD fingerprints of the commercial samples of Ku-Di-Dan retailed in Fujian, Taiwan, Hong Kong and Macau markets are identical with that of Elephantopus scaber L. The relatedness of Ku-Di-Dan among 9 plants may also be estimated by the Similarity Indexes values of the genomic DNA fingerprints.