Metal ion inhibitions of polyacrylamide gel immobilized glucose oxidase were investigated. Both Hg2+ and Ag+ ions were the subjects of this study, in the oxidation of β-D-glucose catalyzed by immobilized glucose oxidase. Electric potential measurement was used as a means to determine the inhibition effect. Experimental results show that the inhibition effects of Hg2+ and Ag+ ions on immobilized glucose oxidase were similar to those observed in free enzyme system. Reversibility of the immobilized enzyme matrix for metal ion inhibition study is reasonably good for a period of 48 hours. The detection level of the metal ions presented in the medium by this electrochemical method is, however, limited.