Dr Douglas Easton is Cancer Research UK Principal Research Fellow and Director of the Cancer Research UK Genetic Epidemiology Research Group at the University of Cambridge. He is a leader worldwide in the genetic epidemiology of cancer, especially cancers of the breast and ovary. He was one of a group who set up the International Breast Cancer Linkage Consortium in the late 1980s, which has been a model for international collaboration, first in mapping the breast cancer predisposing genes, and subsequently in defining the risks associated with mutations and the factors that modify these. His lucid communications of genetic epidemiology has resulted in a more rapid and intelligent application of the results of the research by clinicians than might otherwise have been the case.