The views of previous authors on the elm fall, especially backgrounded by Tauber’s (1965) theory on differential pollen dispersion, are discussed. Five possible explanations are given: climate, competition and edaphical factors, human influence, diseases, selective pollen filtering. For the time being the present author concludes that the most probable explanation for the elm fall is human influence, eventually in interaction with a change in climate. Depending on local, edaphic and ecological conditions, the various factors which may be held responsible for the elm fall, are probably of unequal importance for different regions.