Crystal Violet (BV3), a typical triphenylmethane dye, was degraded by growing cells of Nocardia corallina IAM 12121, although their growth was inhibited at the initial stage of incubation. The dye was degraded at a low concentration, below 5 mumol dm-3. The growth of the cells was completely inhibited at a dye concentration of 7 mumol dm-3. A degradation product of BV3 was identified as 4,4'-bis(dimethylamino)benzophenone (Michler's ketone; MK) by gas chromatography-mass spectrometry. The product was obtained in a reasonable yield since it was not further metabolized by N. corallina IAM 12121.