A measuring unit for measuring a particulate concentration in exhaust gases using scattered light includes a measuring chamber, at least one light source and at least one light sensor, the measuring chamber being situated in the optical path of the light source; and the light sensor records the light scattered by the particulates in the measuring chamber. To detect the intensity of light beam that is relevant for a precise particulate measurement, a monitoring device is provided to detect the intensity of the light beam with the aid of a scattered radiation. The intensity of the light beam is recorded using a monitoring measurement, by ascertaining a scattered radiation and comparing it to a specified reference value for the scattered radiation. With the aid of the comparison, the intensity of the light source is regulated correspondingly and/or the measuring result of the particulate measurement is correspondingly corrected.