Applications of a battery-operated portable syringe driver are reviewed and the Graseby MS16 device is described. Its value in permitting long-term slow infusion of drugs--in preference to intermittent injections--is illustrated by reference to a variety of uses. In size and weight the driver is small enough to permit a patient to wear it even while leading an active life. A custom integrated circuit and a high-efficiency mechanical drive result in such low power consumption that an inexpensive 9V battery will last for up to three months. Applications include heparin infusion, post-operative analgesia, hormone infusions, cancer chemotherapy, domiciliary analgesia in terminal cancer, antibiotics, neonatal infusions, and in human and animal research. One of the most interesting applications has been in the treatment of thalassaemia, extending life expectancy from about 15 years to an indefinite span. The driver incorporates comprehensive safety features.