During the period i946 through 1958, the atoil of Bikini, centered about 11°36'N, 165 22'E, was the site of approximately 22 nuclear detonations. After the atoll of Bikini was selected as a <est area the native population, numbering approximately 166, was eventually resettled in 1948 an Kili, a single island in the southern Marshalis, following brief stays on Rongerik and Kwajalein atolls. Discrete test series were conducted at Bikini Atoll in 1946, 1954, 1956, and 1958 and included both fission and fusion devices. Que to their proximity to the detonation sites, or the vagaries of the weather, all of the islands of the atoll were contaminated to some extent by radioactive fallout. In 1964 and again in 1967, radiological surveys of the atoll were conducted under the auspices of the Division of Biology and Medicine of the U. S. Atomic Energy Commission. The 1967 survey yielded an extensive amount of data relative to the external radiation levers (1) and the concentration of radioactive materials in the marine environment as well as in the edible land nlants and animal life. (2) Foliowing the 1967 survey, an Ad Hoc Committee was convened to evaluate the radiological hazards of resettlement of the Bikini Atoll. The conclusions of the committee included the following statement: ‘The exposures to radiation that would result from the repatriation of the Bikini people do not offer a significant threat to their health and safety," (3) On August 12, 1968, President Johnson announced the decision to return the Bikinians to their atoll. A joint AEC-DASA effort was initiated to eliminate any physical or radiological hazards remaining on the atoll and to prepare the islands of Bikini and Eneu for agricultural redevelopment. program was initiated in February 1969. This phase of the clean-up The data provided in this report result, for the most part, from the radiological clean-up effort associated with this aspect of the program. Air sampling data collected during a follow-up survey in May-June 1970 are also reported. S502