The invention relates to a method for sealing of a circumferentially closed canal. A closure element is secured to one free end of a light guide conducting a laser beam. The light guide with the closure element is introduced into the canal. The closure element is positioned in the region of the canal to be sealed and after positioning of the closure element energy is introduced, so that the closure element melts or softens and remains in this position in the canal and seals it tightly.
