An arrangement for aftertreatment of exhaust gas for lean-burn internal combustion engines such as diesel engines and Otto engines with direct injection has a NOx storage catalyzer installed in the exhaust gas train for reducing nitrogen oxides and at which nitrogen oxides are stored in lean operating phases and these stored nitrogen oxides are reduced in rich operating phases. At least one molecular sieve which keeps sulfur dioxide away from the at least one NOx storage catalyzer is arranged upstream of the NOx storage catalyzer.