The International Harmonized Research Activities Working Group on Intelligent Transport Systems was established to coordinate government research aimed at developing harmonized procedures for the evaluation of safety of in-vehicle information, control and communication systems with respect to human performance and behaviour. It deals with humanmachine interactions in the broadest sense of that phrase. However, it is acknowledged that even in its broadest sense human-machine interactions is only a part of ITS safety. This report describes the activities completed in the past five years, including the formulation of an overall framework for ITS safety assurance indicating the role of the ITS WG within this framework, a series of workshops on the safety test and evaluation of ITS, and definition of priority research problem statements. Recommendations are provided to address the formidable challenges facing the WG. It is anticipated that increased public and government concerns about ITS safety in the future will stimulate increased interest, expectation and funding of harmonized research.