This study is carried out to investigate (1) conditions for the synthesis of polyurethane foam to be used for immobilizing microorganisms, (2) the viability of microorganisms immobilized simultaneously into the pores of a polyurethane foam when the foam is synthesized, and (3) the difference in the ability to degrade PCBs between the immobilized and suspended microorganisms. The results of this study show that polyurethane foam is suitable for synthesizing 10% NCO-prepolymer, water and surfactant in the ratio of 100:2.6:1.2 (w/w), respectively, and the viability of microorganisms (input microbes) immobilized in the foam is high. The input microbes, designated as strain SY5, are isolated from a municipal sewage treatment plant. In addition, immobilized strain SY5 degrades 5-40% more PCB of a PCB mixture (Aroclor 1242) than the suspended strain SY5.