Crude oil being a a dark sticky liquid is heterogeneous mixture of varying molecular weight from which various petroleum products are extracted. There are various technological processes which are used for refining it into consumer products like paraffin oils, gasoline, lubricants, vaseline, asphalt, domestic fuel oil and polymers. The biological, chemical, and geochemical transformations are responsible for formation of crude oil. Several microorganisms are associated with the crude oil formation. The type of substrate and microorganism(ie aerobic or anaerobic) are major parameters responsible for degradation of different petroleum products. For these microorganisms the main source of carbon in crude oil are hydrocarbons which are both aliphatic and aromatic, but also include organic compounds that are mostly the products of crude oil biodegradation. These micro organisms find application in enhancement of oil production using microbiological methods. The present review highlights the biodegradation of crude oil by bacterial community.