An exhaust gas post treatment system for, in particular, a self-igniting internal combustion engine including a catalytic converter that is arranged in an exhaust gas line, a fine particle filter and an introduction device for a reduction agent arranged upstream of the catalytic converter in the direction of the flow of the exhaust gas, and to a method for operating said type of exhaust gas post treatment system. An exhaust gas post treatment system and a method for operating said type of system that is simple to use and compact. This is achieved by virtue of the fact that the catalytic converter is a reductively or oxidatively operated catalytic converter, or that the introduction device, the catalytic converter, that can be operated reductively or oxidatively, and the fine particle filter are arranged in said sequence and in the exhaust line in the direction of flow.