The drill stem has a first drill rod (10) and a second drill rod (11) arranged coaxially to 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 second drill rod (11) is then extended telescopically from the first drill rod (10) by pressurising a cylinder space (28), as a result of which the drill stem is lengthened. 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>
