A system for inserting a cannulated tissue anchor during endoscopic or other surgical procedures. The system incorporates an insertion instrument for inserting into a surgical site of implantation an elongated generally cylindrical tissue anchor having, for example, a plurality of barbs outwardly extending from its body and a transverse head situated at its proximal end. The anchor may be inserted by a single-handed operation of the instrument through a series of sequential pulls of a trigger, each pull affecting motion of a particular element. In a preferred embodiment, three trigger pulls are sufficient to penetrate the site of implantation and deliver the anchor slidably along the needle. The instrument operates with replaceable subassemblies each containing a particular size cannulated anchor, having a longitudinally slidable needle for guiding the anchor into place and a longitudinally slidable push rod for pushing the anchor along the needle.