An ultrasonic surgical instrument having a handle assembly, a waveguide extending distally from the handle assembly, an end-effector located at a distal end of the waveguide, and a clamp assembly removably mounted to the handle assembly, the clamp assembly including a clamp arm pivotally mounted on the distal end of the clamp assembly for pivotal movement with respect to the end effector. The clamp assembly is removably mounted to the handle assembly by axially aligned first and second bayonet mounts, each of the bayonet mounts including a female bayonet coupling having at least one bayonet slot configured to matingly receive a bayonet mounting pin of a male bayonet coupling therein, wherein the bayonet slots extend circumferentially about a common longitudinal axis corresponding to the longitudinal axis of the waveguide. A method of removing the clamp assembly of the ultrasonic surgical instrument is also provided, as well as an ultrasonic surgical shears instrument and a clamp assembly are also provided.
