In October 1997, an expert meeting discussed the use in carcinogen evaluation of emerging short- and medium-term carcinogenicity tests, including transgenic and knock-out mouse models, and results from the use of multistage cancer models. The significance of specific gene alterations found in human and rodent tumours were considered, as well as the significance of genetic and related properties of chemical agents. This IARC Scientific Publication is a sister volume to the IARC Monographs and includes a consensus document setting out the weight that data derived from such tests should be given when making evaluation of carcinogenic risks to humans.