Europe has during recent, years been shocked by disasters from natural events and technical breakdowns. The consequences have been comprehensive, measured by lost lives, injuries, and material and environmental damage. ESReDA wanted in 2000 - by setting up a special expert group on accident investigation - to clarify the state of art of accident investigation practices and to map the use of thoroughly accident investigation in order to learn lessons from past disasters and prevent new ones. The scope was to cover three sectors in the society: transport, production processes and storage of hazardous materials, and energy production. The main method used was a questionnaire, which was sent in 2001 to about 150 organisations. About 50 replies were analysed. The replies showed great variations but also similarities, among others in definition of accident and incident, the objectives of the investigation team, criteria used to start an investigation, the status of the investigation organisation, the flow of information, the composition of the investigation team, and the use of internal or international procedures or rules. Several methods (in total 14 different methods were mentioned) were used for carrying out accident/incident investigations. Most of the respondents were willing to co-operate in one or another way with ESReDA. Although there are important biases in the material, the results from questionnaire are important inputs to the future work of ESReDA Expert group in this field. 3 safety approaches have been identified. (C) 2004 Published by Elsevier B.V.