The enzyme cellulase, a multi enzyme complex made up of several proteins, catalyses the conversion of cellulose to glucose in an enzymatic hydrolysis. The indigenous fungi of Pakistan viz., Trichoderma viride Pers. ex Gray, T. reesei Rifai and T. harzianum Rifai were selected and analyzed on the basis of extent of hydrolyzing zones for the evaluation of their enzymatic activity in solid state fermentation on PDA and plate screening medium (PSM) at pH 4, 5 and 6. PSM at pH 4 depicted best results for all the strains tested. Strains FCBP-142 and FCBP-232 of T. viride, strains FCBP-271 and FCBP-364 of T. reesei and strains FCBP-210 and FCBP-325 of T. harzianum were considered best in their extent of hydrolyzing ability and were selected for evaluation of their cellulolytic activity through submerged fermentation using 3, 5-dinitrosalicylic acid (DNS) method. The maximum enzymatic activity was achieved after 72 hours of incubation at 30 ± 2oC at initial pH 4.