ABSTRACT The Division of Operational Safety's portion of the Pacific Radioecology Program began in 1974 and it is a continuing program to determine the kinds and amounts of radionuclides distributed in the foods, plants, animals, and soils of the Central Pacific, especially the Marshall Islands. As part of this program, Wotje, Ailuk, Utirik, Rongelap, and Bikini atolls were visited in 1976 and samples collected. metric analyses of the samples are presented. Results of the radio. Results of these analyses indicate that 2°Sr and 137¢Cs are predominant in the terrestrial environment and, in addition, 24!Am and 239°240Py are also important in the soil from Rongelap and Bikini atolls. Naturally occurring *°K is the predominant radionuclide in marine organisms, while ©°Co is significant in the tridacnid clams. Amounts of radioactivity vary with distance from the Bikini test site and in relation to the fallout pattern from the March 1954 Bravo test. Thus, samples from Bikini Atoll had the greatest amounts of radioactivity while the northern islands of Rongelap had slightly Tower amounts. The southern islands of Rongelap Atoll and Utirik Atoll had intermediate amounts of radioactivity while Ailuk and Wotje atolls had the least radioactivity of the atolls visited,