To protect the enzymes during fed-batch cellulase production by means of partial enzyme recovery at regular intervals. Extracellular enzymes were partially recovered at the intervals of 1, 2, or 3 days. Mycelia were also removed to avoid contamination. Increases in the total harvested cellulase (24-62%) and beta-glucosidase (22-76%) were achieved. In fermentor cultivation when the enzymes were recovered every day with 15% culture broth. The total harvested cellulase and beta-glucosidase activity increased by 43 and 58%, respectively, with fungal cell concentration maintained at 3.5-4.5 g l(-1). Enzyme recovery at regular intervals during fed-batch cellulase cultivation could protect the enzyme in the culture broth and enhance the enzyme production when the fungal cell concentration is maintained in a reasonable range.