Petroleum hydrocarbon contamination is one of the main environmental challenges. Bioremediation using fungi (Mycoremediation) is the best method to overcome this problem. Consequently, the current study aimed to investigate the tolerance of four fungal isolates to petroleum hydrocarbon and estimate the level of production of cellulase and Mn peroxidase enzymes involved in petroleum oil biodegradation. The fungal isolates were identified as Fusarium solani, Trichoderma harzianum, Aspergillus terreus, and Aspergillus flavus by rDNA sequencing of ITS1 -5.8 S rRNA-ITS2 region. A hydrocarbon tolerance test was conducted using solid minimal media (MM) containing different concentrations of diesel oil, fungal growth rate and dose inhibition response percentage (DIRP) values were recorded. Treated and non-treated Bushnell Haas (BH) broth media were used to test the ability of fungi to secret the target enzymes. The results showed that T. harzianum had the highest tolerance towards diesel oil followed by A. flavus. Diesel oil induced gene-overexpression for cellulase and Mn peroxidase enzymes. A. flavus was the highest producer of cellulase and Mn peroxidase. Finally, all isolates, especially A. flavus and T. harzianum can adapt to high concentrations of petroleum hydrocarbon. Thus, they can be used successfully in bioremediation