Abstract: Effects of 10 organic solvents on the activity of N-Acetyl-β-D-glucosaminidase(NAGase)from the integument of Fenneropenaeus chinensis were investigated.The results indicated that the enzyme was activated in methanol,ethanol,propanol,glycol,glycerol,dimethyl sulfoxide,dioxane,and acetone in low concentrations,but inhibited in high concentrations.It was also activated in 0%to 55% butanol.The enzymatic activity was apparently formaldehyde-concentration dependent.A further study on formaldehyde and acetone showed that the inhibition by either solvent was reversible in high concentrations,and the activation,in acetone in low concentrations.The results demonstrated the varying effects of the organic solvents in different concentrations on the activity of NAGase.