Nitrogen is one of the most limiting inorganic nutrients in the process of bioremediation of crude oil-polluted environments. Enhanced remediation of crude oil polluted soil was achieved, in situ, by accelerating the biodegradation process through seeding with adapted Azotobacter which not only acted as supplier of fixed nitrogen to the indigenous crude oil-degrading bacteria, but also performed some co-metabolic activities. This work describes the capability of Azotobacter in providing activities that are useful in the bioremediation of crude oil-polluted soil and biological nitrogen fixation when in association with indigenous oil-degrading bacteria.