The fluorescence emission wavelength of alpha-chymotrypsin (CT) correlated with its enantioselectivity (E value) for the resolution of DL-tyrosine ethyl ester. The changes in the E value of the CT due to the changes in the solvent composition were closely related to its fluorescence properties (Deltalambda(em)), which were most probably associated with the structural modification of the enzyme. A linear relationship was established between E value and Deltalambdaem in aqueous acetonitrile with high correlation coefficients (r = 0.94).