The Chernobyl accident led to the most serious exposure of a normal human population to ionising radiation, apart from the atomic bombings in Japan. Unlike the bombing, the health impact of Chernobyl has not been comprehensively studied. In some areas (eg thyroid cancer), research has been intensive and informative; in others, little work has been conducted. The validity of extrapolating radiation risk estimates mainly based on atomic bomb studies to exposures of public health concern is controversial. Questions relate to the choice of models for transport of risk between populations; projection of risk over time; extrapolation of risks from external high dose-rate exposure to low dose and low dose-rate exposures from internal radiation. Questions also concern non-cancer risks and the importance of non-targeted effects following low levels of radiation. Chernobyl has an iconic status in the public eye, and the accident provides a unique opportunity to answer these questions, to provide the authoritative studies needed to inform the nuclear debate, and to test novel hypotheses about radiation effects and biology/genetics in general. Because the range of potential studies is so vast, this proposal is for the development of a strategic research agenda on the health consequences of radiation exposure from the Chernobyl accident. The modus operandi will be the assembly of a multidisciplinary group of experts, from within and outside the most affected states, who have considerable experience in the follow-up of the health consequences of the accident. The group will identify and prioritise (short and longer-term) the potential studies, assess their feasibility, cost effectiveness and likelihood of success, and provide a reasoned and comprehensive strategic agenda for future research. The strategic research agenda will be provided within 18 months; detailed proposals for short-term priority research topics will be provided within 9 months.