INTRODUCTION The Division of Operational Safety or DOS (now Safety Standards and Compliance) portion of the Laboratory of Radiation Ecology (LRE) Pacific Radiocology Program (formerly Johnston Atoll Program) began on 1 July 1974 and is continuing, The purpose of this program is to determine the kinds and amounts of radionuclides distributed in the foods, plants, animals, and soil of the Central Pacific, especially the Marshall Islands, and to furnish these data to SSS/ERDA and other appropriate agencies (Lawrence Livermore Laboratory, Nevada Operations Office ERDA) so that they may make an assessment of the dose of ionizing radiation received by the people living throughout the Central Pacific. Here we report the results of the analyses of samples collected on five field trips conducted from April 1974 to August 1975 and analyzed by 31 December 1976. A list of previous reports and letters containing data included in this report is given in Table 1. SAMPLING PROGRAM The field trips noted above are listed in Table 2, Atolls visited in the Marshall Islands are shown in Figure 1. Christmas Island in the Line Islands is about 2000 miles east of the Marshal] Islands, All the trips, except the trip to Christmas Island, were joint surveys with personnel from Brookhaven National Laboratory, Representative biological and soil samples were collected with emphasis on food items common to the diet of the Marshallese people (i.e., fish, coconut, pandanus, breadfruit, coconut crabs, etc.) although non- edible portions of these items were also collected and analyzed. Soils were collected to provide data for estimating future distribution and quantities of radionuclides in the environment and biota, The number of samples, after division into tissues or soil fractions, is shown in Table 2. Over half the samples were biota-plants, fish, clams, and coconut crabs, while just under half were surface (0-2,5cm) and profile (0-100+cm) soil samples. Approximately one-third of the samples came from Bikini Atoll, one-third from Rongelap Atoll, and one-third from Christmas Island, and Wotho, Utirik, Kwajalein, Ailinginae, and Rongerik atolls, In addition to the samples our Laboratory collected, personnel from Brookhaven National Laboratory collected samples,made TLD measurements and took radiation survey readings with sodium iodide (NaI) scintillation detectors and a pressurized jon chamber. The results of the Brookhaven analyses and measurements will be combined with the LRE results in a series of joint reports to the open literature. ANALYTICAL METHODS Gamma-Ray Spectrometry All of the samples were analyzed by gamma-ray spectrometry, either with a 3"x3" sodium iodide (thallium drifted) crystal and 200-channel pulse-height analyzers or with a germanium (lithium drifted) diode detector and 4096-channel, pulse-height analyzer. Soil samples were analyzed on the Ge (Li) system, and the biological samples were analyzed on both systems,