A reusable strip of glucose oxidase (GOD) from Aspergillus niger was prepared by immobilizing the enzyme onto egg albumin membrane affixed oil a plastic strip with a conjugation yield of 1.5 mg/cm(2) and 66% retention of their initial specific activity. The immobilized enzyme showed maximum activity at pH 7.0 when incubated at 37 degrees C for 15 min. A method for discrete analysis of serum glucose was developed employing this strip. The minimum detection limit of the method was 5 mg/dL. Within and between assay coefficient of variation (CV) for serum were <5 and <6%. A good correlation (r=0.972) was found between glucose values obtained by commercial enzymic colorimetric method employing free GOD and the present method. No significant loss in the strip activity was observed after its 150 regular uses for a period of 40 days, when stored in reaction buffer at 4 degrees C. The method has advantage over commercial enzymic colourimetric method that it provides reuse of glucose oxidase with ease.