An ultrasound catheter assembly having a rotatable transducer assembly is disclosed. The ultrasound catheter assembly includes an elongate flexible shaft having a lumen and a proximal end and a distal end. The catheter assembly further includes a drive member that engages the transducer assembly at a distal end of the catheter. Rotation of the drive member in a first direction causes the transducer assembly to rotate in an oscillatory fashion in a second direction.
