Described herein is a surgical instrument for suturing cutaneous tissue, especially scar tissue, when stitching on skin grafts, said instrument comprising a supporting body and a staple body which are hinged to each other so as to be capable of being brought together or apart. A staple magazine is provided on the staple body of the instrument, and an ejector is provided for driving the staples from the staple body into the stitching unit. The stitching unit incorporates a single needle-shaped die with an L-shaped needle, said needle being mounted on the supporting body, and a slot formed at the end of the staple body through which the die needle passes when suturing. The needle-shaped die has two recesses, one of which communicates with the magazine through the groove provided in the supporting body, while the other of which, upon bringing the instrument bodies together, is located against a special groove in the staple body, communicating with the staple magazine and with the base of the slot.