The international collaborative group on HNPCC (ICG-HNPCC) was established in 1989. The original aims of the group were: (1) to develop minimal criteria for the identification of HNPCC, to provide a basis for uniformity in collaborative studies; (2) to improve patient and physician education about HNPCC; (3) to establish international collaborative studies, and (4) to promote the establishment of national (or regional) HNPCC registries. The administrative base of the group is attached to the Netherlands Foundation for the Detection of Hereditary Tumours at Leiden. The Netherlands. An International Informational Center on HNPCC was established at Creighton University in Omaha. The Hereditary Colon Cancer Newsletter (previously the Polyposis Newsletter) serves as a medium for communication about activities of the Group. At present, the Group has about 70 members from 23 countries, and its meetings are held annually. After a period of five years, it can be concluded that the objectives of the ICG-HNPCC have been successfully accomplished. The existence of the ICG-HNPCC has contributed to an increase in awareness of HNPCC among specialists throughout the world. Due to the rapid developments in molecular genetics in HNPCC, it seems very likely that HNPCC will be the first common hereditary cancer syndrome, which can be identified by simple blood DNA tests. The value of the ICG-HNPCC will be extremely important in finding a uniform answer to the question how to utilize DNA technology for the benefit of the human race.