The idea of convening an international workshop on hypertrophic ecosystems originated during the 20th S.I.L. Congress in Copenhagen. A group of about 30 delegates met there in an informal gathering to discuss the specific problems of lakes which have reached a noxious stage of eutrophication. This ad hoc group realized its own specific identity within the limnological community and suggested the organization of a specialized future meeting on hypertrophic ecosystems. After two years of preparatory work, the workshop was fmally held in Vaxjo, Sweden, between September 10 and 14, 1979, on the premises of the University campus. The Institute of Limnology, University of Lund (Professor Sven Bjork), undertook the task of host and organizer. The City ofVaxjo and the University of Lund co-sponsored the event, which was held under the auspices and patronage of the Societas Internationalis Limnologiae. The objective of the workshop was to seek better understanding of highly-eutrophic, disturbed and unstable aquatic ecosystems (lakes, reservoirs and ponds developing noxious algal and bacterial blooms, fluctuating in their water quality on a daily and seasonal scale, producing gases, off-flavor and toxic substances, experiencing periodic anoxia and massive fish kills, etc.), Le., systems requiring corrective measures and new concepts for their solution beyond those generally accepted for 'normal' eutrophic systems.