In a known device for sterilization by ultraviolet radiation, a UV radiator (4) is arranged in a housing (2) made of metal or plastic, which has a radiation outlet window (3) for the emission of UV radiation. The radiation outlet window is covered by a polymer film (7) transparent to ultraviolet radiation. Proceeding from this background, in order to provide a reliable and operationally safe device for sterilization, it is proposed that the housing (2) have a gas inlet (22) for introduction of a cooling gas stream as well as a gas outlet (23) for discharging the cooling gas stream, and that the gas outlet (23) be connected to a measuring sensor (17; 18, 20, 21) for measuring the pressure, mass flow rate, and/or volumetric flow rate of the discharged cooling gas stream.