An enzyme electrode biosensor was used for the amperometric determination of inosine in its tablets by co-immobilizing nucleoside phosporylase and xanthine oxidase on a hydrogen peroxide electrode. As a fundamental electrode the hydrogen peroxide electrode has an advantage of stability in analysis compared with the O2 electrode. The enzyme electrode showed a linear response to inosine in the range of 1~268 mg/L with a response of 60 seconds under a sample injection volume of 25 mL. Based on the enzyme electrode, inosine solutions were determined with an average recover rate of 100.8% and a relative standard deviation (RSD) of less than 0.14% in 20 assays. The lifetime of the enzyme electrode was relative long and could be used continuously at 25oC for 25 days. These results demonstrated that the enzyme electrode biosensor could be used to determine inosine and its derivatives specifically, rapidly, conveniently and economically.