Abstract: A controller for an intracorporeal knot tying device including a hollow handle housing and a slider operator captured in the handle for linear motion between proximal and distal positions. The slider attaches to an elongated, tubular member formed of a shape memory material for carrying a suture thread through an internal passage and a bight formed in the tube. An outer sheath extends from the handle and supports the remaining length of the tube. When a knot is to be formed, a free end of the suture is pulled through tubular member by means of an introducer. A physician advances the operator to displace the distal end of the tubular member to form the bight. Subsequently, the physician retracts the operator to a proximal position to straighten the bight and throw off a knot in the suture thread for subsequent tightening. The operator includes means for grasping the suture.