Abstract: This disclosure describes an implantable microinfusion apparatus used to deliver an infusate systemically to an animal in accordance with a predetermined temporal program. The apparatus utilizes a pump to provide a hydrostatic force for the discharge of a plastic capillary tubing containing a linearly arrayed program of infusates. The tubing is charged with sequential discrete segments of fluid vehicle containing preselected concentrations of the product or products to be infused. The segments may be delimited by intervals of product-free immiscible fluid or the contents of the program tube may be stabilized by the inclusion of a gel in its fluid composition. The volume of the segments determines the infusion time of the various components of the program; the sequential position of the segments determines the order of their infusion, and the concentration of product in the segments determines the rate of their infusion.