This interim report represents a summary of the major findings of the medical survey of the peoples of Rongelap Atoll carried out in March 1965, 1l years after exposure to fallout radiation,and a thyroid survey carried out in September 1965. Complete data for the surveys, including a complete review of past findings, individual findings, and appendices will be published in a report to be combined with complete data of the l2-year post-exposure survey to be carried out in March 1966, Brief Summary of Past Findings These people had been accidentally exposed to fallout radiation following a detonation of a high yield thermonuclear device during experiments at Bikini in the Pacific Proving Grounds in March 1954, Of the inhabitants of the Island of Rongelap, 105 miles away from detonation, 64 people received the largest fallout exposure, an estimated dose of 175 roentgens (r) whole body gamma radiation, contamination of the skin sufficient to result in'beta burns} and significant internal absorption of radioactive materials through inhalation and ingestion. Other Rongelap people away on a nearby island (Ailingnae), where less fallout occurred, received only an external gamma dose of 69 r* The people of Utirik Island about 200 miles east of Rongelap, received an estimated dose of 14 r whole body radiation* Fallout was not visible on this Island, and no beta burns developed. The exposed people were evacuated by planes and ships about two days after the accident, Because of contamination of their home island, the people of Rongelap were not moved back until 1957, when radioactivity had subsided to a safe level, On their return, they were established in a new village built for them, The Utirik people were returned to their island after several months, (following initial medical examinations), since contamination levels there were not considered hazardous, Annual medical examinations have been carried out on the Rongelap people, The Utirik people have been examined four times since the accident, at two to three year intervals, A group of over 200 unexposed Rongelap men, women, and children, who have moved back to Rongelap Island, serve as a comparison population, Detailed information on past findings of the effects of fallout radiation exposure on these people may be found in published survey reports (1-11), Past examinations of the Utirik people showed only a minimal early effect on their blood levels, but with no other findings at any time suggestive of radiation effects, The Rongelap people, on the other hand, had slight transitory gastrointestinal and skin symptoms during the first two days due to radiation exposure, followed by significant depression of blood elements, the development of widespread'beta burns"to the skin with some loss of hair, and measurable internal absorption of radionuclides, However, the gamma dose (175 r) received % ee There were 18 people on Ailingnae (16 of whom are now living) and 157 people On Uterik (about 140 now living). soc wks