Abstract: An arrangement for detecting moisture conditions on a pane, particularly a windshield of a motor vehicle, wherein radiation emitted by a transmitter is coupled by a radiation guide into the pane and is coupled out of the pane onto a receiver. With respect to the production and the dimensions, the design is supported by the measures which provide that the beam entry surface and/or the beam exit surface is/are arranged on the parallel side of the radiation guide facing the circuit board, and that the optical axis of the transmitter or of the receiver is oriented to be perpendicular to the beam entry surface or the beam exit surface and that the radiation guide has at least one input-end or output-end deviating surface with which the radiation that entered the radiation guide is guided at a right angle into the interior of the radiation guide or the radiation which is to be oriented out of the radiation guide onto the receiver is guided at a right angle out of the interior of the radiation guide.