The IARC Monographs Programme on the Evaluation of Carcinogenic Risks to Humans has reviewed, summarized and evaluated 869 environmental agents and exposures as oj June 2000. This large collection includes all relevant published epidemiological data on cancer in exposed humans and results of bioassays for carcinogenicity in experimental animals. Since 1986. cancer data have been systematically supplemented by summaries of other toxicological data that are relevant to assessments of carcinogenic hazard. These include summaries qf genetic and related effects of chemicals. which have been prepared as Genetic Activity Profiles (GAP) by the U.S. EPA in collaboration with IARC. As the Mono-graphs have proved increasingly valuable and influential worldwide. they have evolved into an encyclopedia on environmental carcinogenic risks to humans. However. the Monographs have historically been prepared only as printed books with limited distribution. and the Monographs Programme has needed to adjust to expectations oj wider availability. Since 1998 the evaluations and summaries have been globally accessible by Internet from IARC (http://www.iarc.fr) and the GAP profiles by Internet from EPA (http://www.epa.gov/gapdb/). with the two web sites linked. Improved EPN/ARC GAP database and software. GAP2000. now link GAP profiles directly to the appropriate IARC web pages for summaries of evaluations of a given compound and its overall IARC classification. During the year 2000. by means of optical character recognition (OCR) technology the entire series of IARC Monographs is being converted to an electronic version. The first edition is now available commercially in CD-ROM format and will soon become available on-line at <http://www.gmai.com/IARC>.