This is an attempt to popularize microbial methods for degradation of dyes as dyes are threat to both aquatic and terrestrial life. Physical and chemical method are not found much suitable to treat dyes. Contrary to this microorganisms are capable of complete degradation of dyes by their abilities to utilize range of azo dyes as source of carbon. This book emphasize methods to screen dye decolorizing bacteria, their characterization and ways for analysis of dye decolorization.