Abstract: A skylight with thermal insulation has an input part with light collector and an upper tube for roof passage. A lower tube with a diffuser is included and the roof passage contains an insulation double glazing unit which fixed directly into a collar made of foam insulation. It is especially advantageous if the insulation double glazing unit is fixed in the collar made of a foam insulation material including at least one plastic anchoring holder that embraces the double glazing unit perimeter and extends, with at least some of its parts, above and below the insulation double glazing unit and projects laterally toward the perimeter of the collar made of the foam insulation material.