a dowel construction for anchoring an element in a borehole , comprises , a tubular dowel of a plastic material which is insertable into the borehole and advantageously has means thereon for preventing turning movement thereof relative to the borehole . the tubular dowel has a window opening for accommodating a straddling member which is disposed in the opening between a securing bolt insertable in the dowel and the borehole . the straddling member and the bolt are constructed so that there is a wedge - engagement surface between them which causes radial outward movement of the straddling member into engagement with the borehole when the bolt is moved in a withdrawal direction . preferably , at least two metal straddle bodies are uniformly arranged over the circumference of the bolt and they preferably have cylindrical outer surfaces which are disposed in the window cutouts of the tubular plastic cage forming the tubular dowel . the straddle bodies are arranged diametrically opposite and they are positioned in the window cutouts which are disposed diametrically opposite to overlie the straddling elements .