This Biennial Report of the International Agency for Research on Cancer (IARC) provides a summary of the activities of the Agency during the 2016-2017 biennium. These activities span research areas including descriptive epidemiology, cancer registration and analysis of data on cancer occurrence and trends, basic research into the genetic and molecular aspects of cancer development, pathogenesis, and prevention studies. This report demonstrates the high scientific quality of the work emanating from the Agency and the direct relevance of the findings to cancer control and prevention.