Fiber samples from empty fruit bunches (EFB) of oil palm irradiated at 0, 50, 100, 150 and 200kGy were hydrolysed using commercially prepared enzyme cellulase. The results showed that the amount of glucose produced decreased as the irradiation dose increased. However, the glucose yield was enhanced by crushing the pretreated sample into smaller sizes of 0. 355mm and 0.325mm.