1. 1. Carboxymethyl-Chitin-Remazol Brilliant Violet (CM-Chitin-RBV) was used for a colorimetric assay of chitinase activity in Antarctic krill, Euphausia superba. Comparison with a reductimetric method by end-product detection was carried out by measuring FPLC elution profiles of krill crude extracts with both assays. Both profiles matched significantly. 2. 2. Krill chitinase was highly specific to CM-Chitin-RBV. The assay was characterized by easy handling and a very high sensitivity compared to that of end-product detection. Hydrolysis of CM-Chitin-RBV by N-acetyl-β-d-glucosaminidase, β-glucosidase, β-galactosidase and N-acteyl-muraminidase was negligible. 3. 3. The enzyme characteristics of chitinase from Antarctic krill using CM-Chitin-RBV were: pHopt = 7.5, Topt = 50-55°C, Ea = 52.1 kJ · mole-1, KM = 0.07 ± 0.01 mg · ml-1. © 1993.