A mixing chamber for mixing an additive in an exhaust system of an internal combustion engine, having a single-part or multi-part housing which has an entry opening for exhaust gas having a flow cross-section and having a central entry axis, and which has, arranged downstream of the entry opening, an exit opening for exhaust gas having a flow cross-section and having a central exit axis. A flow-guiding element is arranged within the housing between the two openings, wherein the flow-guiding element is tubular and forms at least one channel having a channel axis, said channel having an inlet and having an outlet, via which the entire exhaust gas stream is guided, in a flow direction parallel to the channel axis, to the outlet having an outlet cross-section, and the flow direction deviates relative to the central exit axis by an angle a of between 20° and 80°. The mixing chamber is to be designed and arranged in such a way that, with a reduced overall length, an improved distribution of the mixture of exhaust gas and additive over the substrate surface is achieved and at the same time deposits of the additive are avoided. A downstream substrate is provided adjacent to the outlet in the direction of the central exit axis, the downstream substrate having a substrate cross-section that corresponds to the outlet cross-section.