as part of the Brookhaven medical examination program. A portable whole-body counter with a standard chair geometry in a shielded steel room was employed (Coh63). Whole-body counts were obtained in the Rongelap and Utirik populations in 1959 (Co60), 1961 (Co62), 1965 (Co67), 1974 (Co75) and 1977 (Co80a). The counting geometry was converted to a scanning type shadow-shield geometry starting in 1965 (Co67). Urine samples were also collected in these surveys and in additional medical surveys conducted in intervening years. The samples were analyzed for their radiochemical content by both USNRDL and the NYO-AEC Laboratories. From 1978 to the present time, whole-body counting measurements were performed with the bed type shadow shield whole-body counter (Co67). a standard chair geometry was once again used. In 1980, All three counting systems were interealibrated and also calibrated against the large Brookhaven National Laboratory 54-detector whole-body counting facility to ensure consistency of the whole-body counting data over the past 28 years. A summary of the sequence of events affecting the whole-body and urine activity measurements on the Rongelap and Utirik people is given in Fig. 1. The detonation of BRAVO in 1954 was followed by the evacuation of Rongelap Atoll at 2.2 days post detonation and then Utirik Atoll at 3.5 days post detonation. After a three month wait, the Utirik people returned in June 1954 and after three years Rongelap Atoll was rehabilitated and occupied in June 1957. Shortly after the Rongelap people's return, the first "in situ’ whole-body counting survey was performed in 1958. The HARDTACK series of nuclear tests in 1958 were the final above-ground tests to be performed by the United States in the Marshall Islands. World-wide atmospheric testing of nuclear devices at other locations continued and peaked during the early 1960's. During the period 1958