The removal of dyes from textile waste water by bacterium is one of the environmental friendly method. The decolorization of azodye metanil yellow studied at various concentration by a bacterial sp. Escherichia coli-K-10 (E.coli K-10). The 0.01 mM, 0.02 mM and 0.05 mM concentration of the dyes was 100% decolorized within 40 hrs, 46 hrs and 52 hrs respectively. Decolorization of dyes was monitored by UV/VIS spectrophotometer. Initially, a highest peak of the dye solution was detected at 437nm (λmax of the metanil yellow). The peak disappears from the decolorized solution, indicating that the decolorization of the dye is due to dye degradation. This bacterial sp. has also been used for the decolorization of other azodyes, methyl orange and congo red. The 0.02 mM & 0.04 mM methyl orange became 100% decolorized during 44 hours but the congo red did not.