“…Leaking oedema means that part of the plasma which leaves the vascular bed in statu nascendi due to the inflammatory stimulus and is not diluted in the extracellular space. It is, therefore, only a fiction which cannot be measured but the calculation of its relative IA concentration seems to be impor tant for the understanding of oedema formation [2], This paper deals with the limits and presumptions which form the basis of this fictive parameter.…”