Suspension-cultured Wasabia japonica cells derived from mesophyll protoplast secreted abundant basic chitinases into the medium. The chitinase isozymes were purified and some of their properties studied. The crude proteins in the culture broth were precipitated with ammonium sulfate and chromatographed on a column using chitin as a chitinase adsorbent. Chitinase proteins were adsorbed specifically on chitin and the percentage recovery of chitinase activity from the crude proteins was 86%. Two chitinase isozymes (CH-1, CH-2) were purified from chitinase proteins by CM-Sepharose cation exchange chromatography. One mg each of CH-1 and CH-2 was obtained from 100 ml of the culture broth. CH-1 and CH-2 were not glycoproteins and have the same molecular weight (approximately 28,000) as determined by SDS-polyacrylamide gel electrophoresis. The isoelectric points of CH-1 and CH-2 were approximately 8.2 and 9.0, respectively. The specific activity of CH-1 was the same as that of CH-2, and both showed lysozyme activity when Micrococcus lysodeikiticus was used as the substrate. They also inhibited the growth of Tricoderma hamatum.