Preface. List of participants. Some memories of Dr Gilberto Righi (1937-1999); M.L. Christoffersen. In memoriam, Professor Perry C. Holt, Ph.D. (1910-2000); S.R. Gelder. Part One: Taxonomy. Descriptions of three Pristina species (Naididae, Clitellata) from Amazonian forest soils, including P. marcusi sp. nov.; R. Collado, R.M. Schmelz. A new lumbriculid genus and species from North America (Clitellata, Lumbriculidae); S.V. Fend, D.L. Gustafson. Taxonomical survey of some stygobiont oligochaetes from the eastern part of France, including description of a new species; J. Juget, M. des Châteliers. A preliminary study of oligochaetes in Poyang Lake, the largest freshwater lake of China, and its vicinity, with description of a new species of Limnodrilus; H. Wang, Y. Liang. New alluroids (Annelida, Clitellata) from Guyana; P. Omodeo, K.A. Coates. Part Two: Diversity and Distribution. Notes on the diversity and distribution of Australian Naididae and Phreodrilidae (Oligochaeta: Annelida); A. Pinder. Oligochaetes in southern European groundwater: new records and an overview; N. Giani, et al. Oligochaete communities in the hyporheic zone of a glacial river, the Roseg River, Switzerland; M. Lafont, F. Malard. Oligochaetes in Lake Towada, Japan, an oligotrophic caldera; A. Ohtaka. Distribution and dispersal capacity of the Ponto-Caspian tubificid oligochaete Pothamothrix. moldaviensis Vejdovsky et Mrázek, 1903 in the Baltic Sea Region; G. Milbrink, T. Timm. Part Three: Morphology and Embriology. Temporal pattern of the double sperm line production in Tubifex tubifex (Annelida, Oligochaeta); S. Boi, M. Ferraguti. External structures used during attachment and sperm transfer in tubificids(Annelida, Oligochaeta); S. Cuadrado, E. Martínez-Ansemil. Mysterious `crystals': found on the epidermal peritoneum of marine tubificid (Clitellata: Annelida) species; K.A. Coates, et al. Pattern formation in embryos of the oligochaete annelid Tubifex: cellular basis for segmentation and specification of segmental identity; T. Shimizu, et al. Part Four: Feeding Biology and Reproduction. Selective feeding by the aquatic oligochaete Tubifex tubifex (Tubificidae, Clitellata); P. Rodriguez, et al. Cocoon deposition of Rhyacodrilus hiemalis Ohtaka (Tubificidae) in Lake Biwa, Japan; T. Narita. Part Five: Ecotoxicology and Bioaccumulation. Utility and relevance of aquatic oligochaetes in Ecological Risk Assessment; P. Chapman. Tubifex tubifex as a link in food chain transfer of hexachlorobenzene from contaminated sediment to fish; P. Egeler, et al. Bioaccumulation of lindane and hexachlorobenzene by the oligochaetes Enchytraeus Luxuriosus and Enchytraeus albidus (Enchytraeidae, Oligochaeta, Annelida); E. Bruns, et al. Part Six: Ecology. Spatial and temporal variations of oligochaetes of the Ivinhema River and Patos Lake on the Upper Paraná River Basin, Brazil; M.C. Montanholi-Martins, A.M. Takeda. The distribution and ecology of littoral Oligochaeta and Aphanoneura (Annelida) of the Natural and Historical Reserve of Isla Martín García, Río de la Plata River, Argentina; L.C. Armendáriz, I.I. César. Effects of Nais elinguis on the performance of an activated sludge plant; C.H. Ratsak. Half a century of oligochaete research in Estonian running waters; T. Timm, et al. Oligochaeta of the Morava and Odra Riv