The drill stem has a first drill rod (10) and a second drill rod (11) arranged coaxially in the first drill rod (10). The second drill rod (11) is telescopically displaceable in the first drill rod (10). When the second drill rod (11) is retracted, a borehole is drilled up to the length of this second drill rod. The first drill rod (10) is then retracted while rotating against the direction of rotation during the first drilling step, as a result of which the drill stem is lengthened by the second drill rod (11) being extended from the first drill rod (10). In a second drilling step, the hole drilled during the first drilling step is lengthened. The telescopic drill stem enables a borehole to be drilled whose depth is greater than the feed distance of the drilling implement used without drill rods having to be coupled to one another. <IMAGE>
