An ultrasonic clamp coagulator assembly that is configured to permit selective cutting, coagulation and clamping of tissue during surgical procedures. An elongated portion of the instrument can be configured for endoscopic applications and has an outside diameter of less than 6 mm. The construction includes an outer sheath and an ultrasonic waveguide positioned within the outer sheath. The waveguide includes an ultrasonically actuated blade positioned at least partially distal the waveguide. A rigid support is positioned between the outer sheath and the waveguide.
