A film diffusional effect on the apparent kinetic parameters in packed-bed reactors containing the enzyme immobilized on the surface of a nonporous support was investigated. A comparison of the plug-flow reactor model equation, expressed analytically in terms of the apparent kinetic parameters, with experimental data showed that the conventional linearized plot based on the reactor model equation was essentially nonlinear. Simulations for the apparent kinetic parameters were made using the intrinsic kinetic parameters and volumetric mass-transfer coefficient previously determined from experimental data. Consequently, the apparent kinetic parameters were found to decrease monotonically with the increase of liquid flow rate. On the other hand, with the increase of reactor-inlet substrate concentration, these constants first increased, passed through a maximum, and finally decreased toward their respective intrinsic values.