This volume is a record of a meeting entitled Heparin and Related Polysaccharides that was held at the Biomedical Center, Uppsala, Sweden between 1-6 September 1991. The meeting was hosted by U. Lindahl, L. Kjellen and I. Bjork, who were helped in their preparations by a scientific advisory panel that included U. Abildgaard, B. Casu, E. Holmer and D. Lane. Altogether, 230 participants from 18 countries attended the meeting, and most were present to be included in a photograph, which is to be found at the end of this volume. The selection of presentations for inclusion in the Symposia of the meeting was made on the basis of the known high quality of the work of the individuals or groups involved. This, we believe, is reflected in the contents of the enclosed articles, which collectively give a comprehensive overview of the present state of knowledge of heparin and related compounds. Some of the areas covered are evolving or controversial and the views expressed in each article should be regarded as those of the author(s). The authors have taken various amounts of care to define all their abbreviations and some familiarity with the different forms of nomenclature used in the fields of polysaccharide chemistry and of the coagulation proteinases and their inhibitors will assist the reader.