The German Society of Parasitology (Deutsche Gesellschaft für Parasitologie) was founded in 1960 and its 21st biannual meeting took place in Würzburg, Germany, from March 17 to 20, 2004. Whereas interim meetings that are being held every other year focus on specific topics of parasitology, such as the symposia on "Life in Vacuoles" in 2003 and on "Immunomodulation by Parasites" in 2001, the general biannual meetings cover a wide range of topics. This year's meeting at the University of Würzburg was organised by Klaus Brehm and Matthias Frosch (both at the Institute of Hygiene) and Heidrun Moll (Institute for Molecular Biology of Infectious Diseases). It was attended by more than 500 scientists from 16 countries who presented 181 research projects dealing with the topics defence mechanisms and immunology, genomics and proteomics, epidemiology, cell biology and biochemistry, chemotherapy and vaccines, parasite classification and morphology, vectors, intermediate hosts, and veterinary parasitology. In addition, six plenary lectures highlighted the subjects of comparative nematode genomics, cell biology, immunology, and parasite eradication programmes.