An important aspect of the treatment of sludges and slurries is the emission of odour. International cooperation in odour control and odour measurement is only possible if the results are comparable. For this reason, Working Party I of the COST Project 681 established a sub-group to study the international development of odour measurement techniques. The inventory made by this sub-group resulted in a proposal for a workshop on olfactometric measurement in order (1) to exchange experiences with different olfactometers, and (2) to consider the possibilities of more harmonised measurement. As odour measurement is not a goal in itself but a step on the way to odour control, it was decided to combine this workshop with a workshop of the FAO Sub-network 2 devoted to reduction of odour in animal farming.