Production Of L-methionine by immobilized pellets of Aspergillus oryzae in a packed bed reactor was investigated. Based on the determination of relative enzymatic activity in the immobilized pellets, the optimum pH and temperature for the resolution reaction were 8.0 and 60degreesC, respectively. The effects of substrate concentration on the resolution reaction were also investigated and the kinetic constants (K-m and V-m) of immobilized pellets were found to be 7.99 mmol dm(-3) and 1.38 mmol dm-3 h(-1), respectively. The maximum substrate concentration for the resolution reaction without inhibition was 0.2 mol dm(-3). The L-methionine conversion rate reached 94% and 78% when substrate concentrations were 0.2 and 0.4mol dm(-3), respectively, at a flow rate of 7.5 cm(3) h(-1) using the small-scale packed bed reactor developed. The half-life of the L-aminoacylase in immobilized pellets was 70 days in continuous operation. All the results obtained in this paper exhibit a practical potential of using immobilized pellets of Aspergillus oryzae in the production Of L-methionine.