ABSTRACT Rapidly increasing demand and depleting reserves of crude oil have pushed scientific community to work towards finding alternatives of the fossil fuels. Lignocellulosics based 2G ethanol is being looked as a sustainable eco-friendly alternative of the crude oil to be utilized in transportation sector. Despite decade-ful of research on developing 2G biorefineries, pretreatment of LCB still remains one of the major bottlenecks. There are several physical and chemical pretreatment methods in practice since years but high process cost, production of fermentation inhibitors and toxic waste generation are some of the major concerns associated with them. Biological pretreatment is a good alternative in this direction which offers a greener and cleaner pathway to get rid of recalcitrant lignin fraction that obstructs the access of cellulolytic enzymes to target sites present in LCB. Although biological pretreatment strategies are being explored from past couple of decades but development of an economically viable and efficient technique is still under research. The recent developments in this field have indicated towards formulation of bacterial cocultures, fungal co-cultures and bacteria-fungi co-cultures to attain efficient bioconversion of lignocellulosic biomass into ethanol.Through this article, an effort is made to review various biological pretreatment strategies in practice with main emphasis on the enzyme and microorganisms involved, regulation of ligninolytic enzymes, and process parameters affecting the success of the strategy adopted.