Implantable vascular access devices are used increasingly when the patient's drug regimen involves highly irritating drugs or the need for a longterm vascular access site. Customer inquiries and a brief review of the literature indicate a lack of standardization regarding the volume of Heparin Lock Flush Solution needed to flush these devices. Therefore, the volumes of three commonly used implantable vascular access devices and two extension sets were measured in the laboratory. Results indicate that current flushing recommendations call for a larger volume of heparin solution than is needed to clear the devices adequately. Awareness of the volumes of these devices may help practitioners to establish a standardized heparin flush protocol that will lead to a reduction in the amount of excess heparin injected into patients with implantable vascular access devices and at the same time maintain patency of the device.