In a method for producing a lengthwise welded metal tube with an outside diameter of 1 to 6 mm, whereby a metal band is shaped into a lengthwise slotted tube by a forming tool, and the lengthwise slot of the tube is welded by a laser welding installation, the tube to be welded passes immediately before and immediately after the welding point area through a guide that guides the surface of the tube to keep the edges of the band in contact with each other and keeps the welded seam stress-free. The jaws of a clamping tool grip the welded tube immediately downstream of the guide to keep it from twisting.