An antithrombin III mutation database was collated and published in L99L by a group of investigators working on the molecular basis of antithrombin III deficiency (1). Soon after, under the auspices of the ISTH SSC, an Antithrombin III Working Party was formed of those involved in the preparation of the database, with the instruction to report to the "Thrombin and its Inhibitors" SSC on the developments in this and related areas. This document is one outcome of the work of the Antithrombin III Working Party and is a partial report of the deliberations of the "Thrombin and its Inhibitors" SSC Meeting held in Munich, July 1992. Other items discussed at this meeting included the nomenclature of the plasma coagulation inhibitors. Three alternative names were considered for this inhibitor, antithrombin III, antithrombin and thrombin inhibitor I. No unanimous view emerged regarding the name, other than the rejection of the term thrombin inhibitor I. For this report, the historical name antithrombin III will be used, despite the preference for anti. thrombin by the majority of the authors of this database. This is in deference to the journal, Thrombosis and Haemostasis, pending any final decision of the SSC regarding nomenclature. The intention behind the production and updating of the antithrombin III database has been to provide a readily accessible and up-to-date source of known mutations of antithrombin III. The complex effects of some mutations on structure/function relationships of the protein can only be indicated. For more information on this and on possible mechanisms involved in gene mutation (see below for brief consideration of mutations involving CpG dinucleotides), the reader is referred to the original papers and to several reviews in this area (2-6).