Interstitial tumor therapy guided by imaging techniques is a minimally invasive and promising surgical approach which will become clinically practical only when simple and safe modalities of control of vascular supply to tumors are available. In a novel experiment utilizing the Advanced Technology Laboratories Mark IX/HDI (Bothell, Washington) ultrasound scanner, the carotid artery (approximately 2.5 mmin diameter) of a New Zealand white rabbit was identified and then clamped using the Endo-Clip' disposable applier with medium-large clips. The Mark lx, equipped with a 10 MHz linear array transducer, guided and localized the tip of the EndoClipt1 tO therabbit's carotid artery. The artery was then clamped, and the Mark IX showed the cessation of blood flow within the carotid. The experimental result is revolutionary since the ultrasound not only provided the visualization of the arterial vessel, but also helped guide the surgical instrument used for clamping. The scanner provides a diagnostic medium comparable to that of Digital Subtraction Angiography, but without the need of intravenously injected contrast materials. More importantly, ultrasound has the ability to discern not only anatomical features, but also foreign objects, such as surgical instruments or clips. This additional feature of ultrasound, discerned from our experiment, provides further insight into the use of this kind of diagnostic modality as a monitor during vascular surgical procedures. A minimally invasive transcutaneous entry procedure is thus possible with the use of high spatial resolution scanner guidance to desired vessels. The ramifications of this experiment are far reaching, since technology with greater soft tissue contrast and the abifity to visualize the irreversible effects of energy deposition in tissues exists with Magnetic Resonance Imaging (MRJ). The feasibility of this approach has been ascertained via the above experimental fmding, and now needs to be further pursued.