The purpose of this study was to evaluate the flow rate of elastomeric balloon infusor composed of rubber or silicone materials. Two models were studied: the Baxter Twoday Infusor and Advance Silicone Infusor. Each infusion device has a preset flow rate of 2 mL/hr. Fifteen units of each device were filled with 100 mL of normal saline. The flow rate was measured gravimetically using an electronic balance. The internal pressure of the balloon infusor was measured with a Digital pressure meter via the pressure transducer. The monitored internal pressure of the two kinds of infusor was not maintained uniformly during the entire delivery period, which was divided into 3 phases: the phase of decreasing, maintained, and increasing pressure during the delivery of drug. Both devices initially infused at a relatively high rate, followed by a somewhat steady flow rate. The flow rate distinctly increased in the small residual volume. The flow rate of the balloon infusor used in this study was not sustained uniformly during the entire delivery period and was in proportion to the internal pressure of the infusor regardless of the materials.