In order to make available an exhaust gas system for a combustion engine with an external housing, which contains at least one rear shell and one front shell, and with a catalyst chamber, in which at least one catalyst element is arranged, and with an exhaust gas duct, from which exhaust gas is conveyed from the catalyst chamber, said exhaust gas system including few components and being able to be produced cost-effectively and wherein harmful thermal stresses in the components of the exhaust gas system are largely avoided, the catalyst chamber also forms the exhaust gas duct. The catalyst chamber has at least two chamber halves, and the exhaust gas duct is provided materially uniform and in one piece in at least one chamber half.