Abstract: A method whereby a hollow organ is compressed from two sides along an intended line of section after which simultaneous dissection and welding of the edges of the cavities formed is carried out by moving a focused laser beam along said line.The degree of compressing the organ's walls is within the range from 1/5 to 1/2 of the initial thickness of said walls.A device for accomplishing said method has a pair of clamping jaws drawn together or apart by means of clamps. One of the jaws serves as a guide path for a carriage, mounted on which is the exit portion of a light guide with a focusing lens. The light guide is connected with a laser. A through slot is made in one of the jaws along the line of intended section and a groove is provided on the other jaw opposite said slot. The walls of the slot and the groove have a surface reflecting the laser beam.