complex and socio-economically impaired population, it was considered that detection of a statistically significant increase in fatal cancers attributable to the radiation exposure would be unlikely. Based on the experience of the Marshallese Islanders, hypothyroidism and thyroid tumors would have been predicted, particularly among the children under 15 years who comprised > 40% of the population exposed in 1954. The early medical management and subsequent monitoring and care provided the inhabitants of Rongelap, Ailingnae and Utirik were entirely appropriate in nature and scope even by today’s standards, especially when considering the remoteness of the accident from basic medicalfacilities and personnel. While someofthe clinical laboratory investigations now might be considered esoteric given the levels of exposure and the limited clinical facilities, events of this magnitude were rare during the early days of the nuclear era. Also, the medical teams were charged with evaluating the relationships between the inhabitants’ health and their prior exposure to radiation. In hindsight, attempts to identify a comparison population for the purpose of epidemiologic analyses might be considered unnecessary, given the heterogenicity ofthe available populations, the potential for systematic error, bias and other limitations and uncertainties in the data retrieved. Nevertheless, epidemiologists are noted for making the best of the data available, and this was an opportunity to be seized rather than justified. If an accidentof similar type and magnitude happened today, many improved approaches and methods would be available for detailed and extensive clinical and radiation dose assessments for individuals, and to manage and analyze data. Whetherfull scale epidemiologic studies would be justified, is doubtful. This issue was addressed in 1990 for the Committee on Interagency Radiation Research and Policy Coordination with the conclusion that thorough evaluation and follow-up of the exposed populations are indicated both from scientific as well as the humanitarian perspective. It also was recommended that plans for collection of adequate and appropriate data be developed but implementation of major epidemiologic studies to test hypothesis should be considered on the basis of the potential (power) of such a study to yield definitive results. iii SUPP Ob