The main purpose of this research was to investigate the antitumor and antimicrobial activities of the chitooligosaccharides containing hydrolyzates obtained from the hydrolysis of chitinous materials (such as chitin, chitosan, and squid pen) by bromelain. The optimum preparations were gained in the hydrolysates of squid pen powder hydrolyzed at pH 5, 37 degrees C for 2 days by 0.1% bromelain. The hydrolysates had an 80% inhibitory activity on phyto-pathogenic mold Fusarium oxysporum. Chitooligosaccharides were recovered from the hydrolysates and were used for tumor cell surviving test. Surviving rate of the human leukemic U937 cells was reduced to 69% by the chitooligosaccharides. The solution of 0.1% of water-soluble chitosan was also hydrolyzed for I day at pH 5, 37 degrees C by bromelain. The resultant hydrolysates contained the highest chitooligosaccharides, which had inhibitory effect on Bacillus subtilis and also had 40% inhibitory activity on human pathogenic mold Aspergillus fumigatus. Surviving rate of mouse CT26 colorectal adenocarcinoma cells was reduced to 57% by the chitooligosaccharides. This is the first publication of enzymatic reclamation of squid pen (fishery processing waste) for the preparation of antitumor and antimicrobial materials. (c) 2007 Elsevier Ltd. All rights reserved.