The invention relates to an exhaust gas treatment device for an exhaust system of a combustion engine, more preferably of a road vehicle, with a housing enveloping at least one interior space, and with at least one through-pipe penetrating the interior space without interruption and which at two fastening points distant from each other is connected to the housing in a fixed manner.For compensating thermally related expansion effects the through-pipe between the fastening points can comprise at least one expansion compensation section, in which a wall of the through-pipe comprises slits penetrating the wall alternating in circumferential direction and strips protruding relative to adjacent wall sections of the through-pipe.