In this article, the immobilization of prostaglandin synthetase on n-alkyl or aryl amino-agar beads by hydrophobic adsorption is reported. The effects of different hydrophobic groups in the agar beads, pH of buffer, concentration of salts on the adsorption of prostaglandin synthetase, and the properties of immobilized prostaglandin synthetase were also studied. The results showed that 20-35 mg of microsome containing PG synthetase (protein content 8-15 mg) could be adsorbed on each gram of n-dodecylamino-agar beads after suction drying the gel in the buffer of pH 5.5 (containing 0.5 mol/L KCl), 0.1 mol/L citric-phosphate at 4 degrees C. The remaining immobilized enzyme activity was over 80%. The optimum pH of immobilized PG synthetase is 8.0, similar to that of the native enzymes. The thermostability of immobilized PG synthetase in the buffer containing 0.5 mol/L KCl was increased. Immobilized PG synthetase was used as a catalyst of synthesis of prostaglandin E(1). The preservation of activity after 10 working cycles was 86.2%.