Planning for a major survey effort by the Division of Biology and Medicine began early in 1967. The emphasis was on delineation of the external radiation fields, particularly at locations of past and future habitation, and on obtaining more measurements on all islands, including the smaller islands near test locations. Dr. Edward Held, University of Washington Marine Radiobiologist was appointed survey team leader. Team membership included personnel from AEC (BM, OS, HASL), AEC contractors, U. S. Trust Territory, and the U. S. Naval Radiological Defense Laboratory. Four native workers were added to the team in Kwajalein. The survey team spent 16 days at the atoll in April-May 1967 conducting an extensive survey of external radiation levels. Except for Adrikon, a very small island in the Southwest corner of the atoll, all fourteen islands and the two complexes of islands joined by man-made causeways were surveyed. studies on Bikini Island. Seven days were spent with In addition to monitoring external radiation, samples of food items, vegetation, and soil were collected and analyzed for radionuclide content. External radiation levels and the radionuclides contributing to those levels were found to vary from island to island. On islands more remote from testing activities such as Eneu and Bikini, the major contributor to the external gamma field is cesium-137. pV The (90