This guideline describes the measurement strategy for the detection of moulds in indoor environments. The prime objective of this guideline is to provide assistance in locating mould sources. The methods and procedures presented do not allow any exposure assessments with regard to the room occupants. Furthermore, this guideline presents different sampling and analysis methods together with a description of their applicability and the interpretation of the measurement results. This guideline provides guidance for the field inspection and inventorying of the affected room or building and recommends suitable sampling and analysis methods to maximize the comparability of the measured data obtained for a given measurement objective. The application of this guideline requires the knowledge of guidelines VDI 4300 Part 1, VDI 4252 Part 2 and VDI 4253 Part 2.