During the mid 1940s through 1958, the U.S. conducted high yield weapons tests at Bikini and Enewetak Atolls. These areas were contaminated with fallout from the tests. A restoration program, concentrating on the main residence islands of Bikini and Eneu Islands at Bikini Atoll, began in 1969. Approximately 30 Trust Territory residents including some former Bikini Atoll inhabitants participated in the initial cleanup and redevelopment of the Atoll. During subsequent years, the Bikini population increased to some 140 individuals at the time of their departure in August 1978, Between 1969 and 1974, scrub vegetation on Bikini and Eneu Islands was cleared and indigenous food crops were planted. These crops consisted mainly of coconut, pandanus and breadfruit trees, but included a garden development where squash, papaya, bananas and other crops were grown (Ro77). During the maturation interval for most of the tree crops (5-7 years), the majority of the food consumed on Bikini Island was imported. As the local vegetation developed, the diet became less restricted to imported foods so that by 1978, the diet contained sustantial quantities of locally grown items. Bioassay and external exposure monitoring programs were initiated for Bikini Island residents in anticipation of the changing dietary situation, and with the realization that it was essential to do personnel monitoring on those individuals living on Bikini Island. From the period 1974 §8 1978 the Bikini people exhibited ever increasing body burdens of Cs and Sr. Based on the intake pattern exhibited by adults we estimated a committed gffective dose equivalent of 8.4x19, Sv (0.84 rem) from internally deposited Cs, 2.0x10 ~ 3.2x10 Sv (0.0032 rem) from ~~Co. Sv (0.20 rem) from ~~Sr and External radiation exposure minus natural background was 5.5x1073 Sv (0.55 rem). years. The average time the exposed adults were at Bikini Atoll was 4.5 The people were removed to Kili Island in August 1978 and we are anticipating further cleanup activities at Bikini Atoll. ACUTE EXPOSURE INTRODUCTION The subject of this presentation is a description of the major health physics aspects of fallout exposure of the inhabitants of Rongelap, Utirik and Sifo Islands on March 1, 1954. radiation measurements. External exposure was estimated based on gamma In order to estimate thyroid dose, an estimate was made of the amoung of fallout activity taken into the body. This was done by reexamining the I excreted from persons who were at Rongelap. The other components of fallout taken into the body had to be inferred from studies on fallout composition. Initially, fallout composition was assumed and nuclide activity concentrations in air, water and food were established on the. basis of meteorological and archival soil study results. Further study led to dose estimates based on actual BRAVO fallout composition, rather than estimates based on hypothetical compositions. Finally, knowledge was gathered about the intake pathway and the time post detonation at which intake was likely to have occurred and this was factored into the thyroid absorbed dose estimate. The limitations of this work are 1) thyroid dose estimates have a large standard error 2) thyroid dose estimates apply for a unique situation and