AbstractThe history of groundwater ecological research carried out during the last 75 years along the Rhǒne, Rhine and Danube alluvial plain is reviewed. Phreatobiology, a concept introduced by Motas (1958), is denned, and the main phases in the development of this research direction dealing with the study of groundwater organisms living in the unconsolidated sediments are reviewed.During a preecological phase of phreatobiology, students were interested mainly in the discovery of exciting groundwater organisms and the explanation of their origin. Modern groundwater ecological research began with Schwoerbel's investigations of the Upper Danube alluvial sediments in the beginning of the 1960s. Progress in phreatobiological research was made during the last twenty years through the description of the complex mosaic of habitats in the Rhǒne and Danube plains by French and Austrian students, by applied and theoretical research carried out on the Upper Rhine by S. Husmann.Three main directions of modern groundwater ecological research are discussed in detail: the ecotone approach developed by students of the University of Lyon on the Rhǒne; the ‘minimalist’ approach, the study of a reduced groundwater ecosystem in the wetland area of the Danube, near Vienna, carried out by an interdisciplinary team; and finally, the ecotoxicological approach developed by Dutch scientists working on the lower Rhine plain. Modern ecological research has inspired groundwater ecology with new concepts and ideas, so that phreatobiology has today expanded into a progressive field of research which complements the other two limnological subject areas, the study of lentic and lotic surface