An actinomycete, Nocardia sp. strain 835A, grows well on unvulcanized natural rubber and synthetic isoprene rubber, but not on other types of synthetic rubber. Not only unvulcanized but also various kinds of vulcanized natural rubber products were more or less utilized by the organism as the sole source of carbon and energy. The thin film from a latex glove was rapidly degraded, and the weight loss reached 75% after a 2-week cultivation period. Oligomers with molecular weights from 10 to 10 were accumulated during microbial growth on the latex glove. The partially purified oligomers were examined by infrared and H nuclear magnetic resonance and C nuclear magnetic resonance spectroscopy, and the spectra were those expected of cis-1, 4-polyisoprene with the structure, OHC-CH(2)-[-CH(2)-C(-CH(3))=CH -CH(2)-](n)-CH(2)-C(=O)- CH(3), with average values of n of about 114 and 19 for the two oligomers.