A flow injection system was developed for the determination of glucose based on fiber optic chemiluminescence measurements. The hydrogen peroxide produced from the glucose oxidase catalyzed reaction was quantified by measuring the intensity of luminol chemiluminescence in the presence of excess ferricyanide. Glucose oxidase was immobilized on aminopropyl glass using glutaraldehyde and packed in a reactor. The chemiluminescence was transported to the detector using an optical fiber. The system responds linearly to glucose in the concentration range 0.20 mM up to 2.5 mM, with a relative precision of 5%. Several fruit juices were analyzed for their glucose content and the results were compared with a standard AOAC procedure.