Abstract: There is provided a method and apparatus for locating leaks in flat roofs, particularly in flat roofs covered with a gravel layer, plants or the like, and wherein it is provided that a moisture location discovered below the flat roof is connected with a positive terminal of a pulse generator, the negative terminal of the pulse generator being connected with a metallic gutter edge of the flat roof, and the flat roof being scanned by measurement sensors for the purpose of measuring the pulses passing through the moisture path to the corresponding leak location and from the leak location through the moist, flat roof. The measurement sensors are connected with a measurement device for measuring the impulse amplitudes, which become successively weaker as they progress from the leak location to the rim of the flat roof.