A cellulase with activity as a cellobiohydrolase [EC3.2.1.91] was purified from the intestinal juice of the giant snail Achatina fulica. The enzyme (M(r) = about 23,000, and pI = about 5.3) also had a weak beta-glucosidase activity. The amino acid sequence of the N-terminal 20 amino acids was analyzed, and no similarity was noted for sequences of other known cellobiohydrolases.