A new quartz crystal impedance hyaluronidase sensing technique, which is based on the changes in viscosity and density during the enzymatic hydrolysis of chondroitin sulfate (CS) by hyaluronidase (HAse), is established in this paper. The variations of equivalent circuit parameters of the piezoelectric quartz crystal (PQC) during the enzymatic degradation are discussed. The initial hydrolysis rate of CS by HAse is obtained from the changes in viscosity and density with incubation time. Kinetic parameters (the Michaelis constant K-m and the maximum hydrolysis rate V-max) of the degradation process are estimated by using a linear method of Lineweaver-Burk plot. K-m is 2.73 +/- 0.20 mg ml(-1) and V-max is -(5.43 +/- 0.38) x 10(-4) kg m(-2).s(-1/2).min(-1).