Abstract: An ultrasonic surgical instrument including an ultrasonically actuated blade or end effector having a treatment portion. The blade can define a central axis and at least one axis which is transverse to the central axis, wherein the transverse axis can lie within a plane which is perpendicular, or normal, to the longitudinal axis and can define a cross-section of the treatment portion. Such a cross-section can include a central portion and a step extending from the central portion, wherein the central portion can comprise a width, and wherein the step can comprise a cutting edge. In at least one embodiment, the cutting edge can be defined by first and second surfaces which define an angle therebetween. In various embodiments, the position of the cutting edge and/or the angle between the cutting edge surfaces can be selected in order to balance the blade with respect to the transverse axis.