A mixer mixes exhaust gas (A) flowing in an exhaust gas-carrying duct of an internal combustion engine with reactant (R) injected into the exhaust gas-carrying duct. The mixer includes a mixer body (32) with a reactant receiving duct (48), an exhaust gas inlet opening arrangement (70) with a plurality of exhaust gas inlet openings (72, 74, 76, 78, 80) leading to the reactant receiving duct, and at least one release duct (62, 66) leading away from the reactant receiving duct (48) with a release duct opening (64, 66) for the release of a reactant/exhaust gas mixture from the mixer body (32).