A blood warmer (10) has a first heating plate (12) and a second heating plate (14) as well as an exchangeable conductor (18, 20, 22, 24) for blood, which is arranged between the first heating plate (12) and the second heating plate (14). The blood warmer (10) has an inlet (66) and an outlet (68) for blood to which the conductor (18, 20, 22, 24) is fluidically connected. Due to the roughness of the surface (46) of the conductor (18, 20, 22, 24), an intermediate space (50) remains between the first heating plate (12) and/or the second heating plate (14) and the conductor (18, 20, 22, 24). A medium (52), which has a higher thermal conductivity than air, is at least partially statically arranged in the intermediate space (50). The blood warmer (10) may also have an electromechanical oscillating circuit and/or a vibration motor.