Abstract: A method and apparatus for removing plaque, fatty deposits, and other occlusions from blood vessels using ultrasonic energy. The method and apparatus has particular application in removing plaque from the carotid artery in a non-thermal manner. The apparatus is designed to have as small a cross-sectional profile as possible, therefore allowing the apparatus to be used in a minimally-invasive manner. As a result, the apparatus can be used in both surgical and outpatient treatment with minimal post-operative complications and minimal damage to areas other than the area of treatment. An ultrasonic probe may include aspiration channels on its outer surface. An aspiration sheath may surround the ultrasonic probe, such that the location of an aspiration port may be varied axially relative to the ultrasonic tip.