The quality of natural water resources has been depleting due to the lack of proper treatment of effluent discharged from textile dyeing units. To impart color to the fabrics, synthetic dyes have been used which pose a serious threat to the environment due to their toxicity. The Complex structure of dyes has made them difficult to degrade. Therefore a perpetual method is needed to eradicate the dyes. Conventional methods arouse but they are not efficient as the derivatives of the complex dyes remain in the water even after the treatment and are expensive. In recent times, nanoparticles are found to be wholly effective. Notably, nanoparticles which are synthesized by biological methods took up many applications such as wastewater treatment, drug delivery, biosensors etc. Biological methods are eco-friendly, easily approachable and cost- effective. Biologically synthesized nanoparticles were found to have the ability to degrade toxic dyes. This review emphasizes the biological sources used for the synthesis of various metal nanoparticles, mechanism of degradation and their dye degradation efficiency. © 2019