Abstract: A drilling tool adapted to produce a radial enlargement along a cylindrical elementary drilled hole in concrete masonry. The tool comprises at least one cutter which is mounted in a slot in a drill sleeve which enters the elementary drilled hole, this cutter being held so as to be fixed in the peripheral direction and axially but movable radially by an inner spreader element, provided with chamfered surfaces, which is movable axially relatively to the drill sleeve. This spreader element is in one piece with the shank, which is directly rotatively driven, is movable axially relatively to the drill sleeve and is close-fitted therewith in the peripheral direction. The end of the drill sleeve projecting out of the elementary drilled hole is connected to an abutment piece which determines the location of the radial enlargement along the drilled hole.