PCR based on specific primers was employed for detection of important cellulase genes (CBH1, EGI and EGII genes) in the genomes of eighteen Trichoderma isolates recovered from Egyptian soil rich with the agricultural wastes. The Trichoderma asperellum (Tm4) isolate that exhibited the highest hydrolysis zone was selected for evaluation their cellulase activities via solid state fermentation on media supplemented with rice straw and sugarcane bagasse as sole carbon sources.  The results showed that the highest FPase, CMCase, Xylanase activities were obtained when rice straw was used as sole carbon source as compared to sugarcane bagasse. In addition, the cellulase activities were better in each the untreated rice straw and sugarcane bagasse than the alkali pretreated rice straw and sugarcane bagasse. The C/N ratio was decreased, while the weight loss was increased in the treatments inoculated with Trichoderma as compared to control. Moreover, the pH values of each alkali pretreated rice straw and sugar cane bagasse were shifted toward the acidity. Meanwhile, the pH values of untreated rice straw were shifted toward alkali state.