Among fifty fungal isolates were isolated from crude oil polluted soil samples collected from different localities in Upper Egypt (Assuit), Fusarium oxysporum C61 was selected for crude oil biodegradation due to of its high metabolic activity. The identification process of fungal genera and species resulted in fifty fungal isolates belonging to twenty six genera presented as follows: ten strains of Aspergillus, nine strains of Penicillium and one strain of Absidia, Cunninghamella, Eupenicillium, Fusarium, Nectria, Phoma and Syncephallastrum. The influence of various, pH values, nitrogen sources, phosphrous sources, amino acids and vitamins were investigated to obtain optimal crude oil biodegradation. The results were found to be, pH 8, sodium nitrate, ammonium phosphate, phenylalanine, and vitamin B1, respectively. The chemical compositions of the residual crude oil were analyzed by gas chromatography mass spectrometer (GC-MS). The ability of fungal isolates to degrade crude oil as sole carbon and energy source under all optimal conditions reveled changes in some components of crude oil (not shown). Analysis of hydrocarbon components of the crude oil substrate left after the growth of F. oxysporium (referred to as residual crude oil) resulted in the presence of tridecanes, pentadecanes, hexadecanes, and dodecanese in reaction products, which brought about greater reduction in peak of crude oil components, relative to those of the control (undegraded).