rr reports to the Health Services of the Govern- ment of the Republic of the Marshall Islands on public health matters identified by the Brookhaven medical teams. In 1983-1984 these public health reports included information concerning the prevalence of hepatitis B, the growth of Marshallese children, tuberculin skin-test positivity, a survey forsyphilisin young adults, and the prevalence of anemia in Marshallese children. It was a related investigation, which identified high levels of fecal contamination of well water on Rongelap and Utirik, that led to the construction of a large concrete cistern on each of the twoatolls. This was a joint effort of the Departmentof Energy Pacific Area Support Office and the Government of the Republic of the Marshall Islands. The contents of the public health reports are always presented to the Marshallese communities at the time of the “town meetings” which precede each medical examination session on the atolls visited by the medical team. Exposure Groups As in recent years, the medical program continues to examine and treat some 1200 to 1400 persons annually, half of whom are children. For purposes of comparison, however, the exposure groups defined in the last Brookhaven National Laboratory report are the same as those from whichthe statistics herein have been collected (Adams et al. 1984b). They are de scribed below: Rongelap Now numbering 50, this group received an estimated 190 rads of absorbed external gamma radiation. Of the 67 persons originally exposed in 1954, 3 were in utero. Ailingnae Nineteen persons, including 1 in utero, received an estimated 110 rads of absorbed external gamma radiation. Twelve persons are now in this group. Utirik One hundred twelve persons are currently alive in this group. The original 167 individuals who were exposed, including 8 in utero, received an estimated absorbed external gamma radiation dose of 11 rads. Comparison In 1957, 86 unexposed Rongelap persons were individually matched by age and sex with the combined exposed Rongelap and Ailingnae groups (Conard et al. 1958). Sixty persons remain in this matched group, against which the overall survival of the exposed population is compared (Figure 1). A second, larger unexposed group continues to be followed. Currently numbering 135, the age and sex distributions of its members are statistically similar to those of the combined Rongelap-Ailingnae groups and the Utirik group (Adams et al. 1984b). It is this larger unexposed population that is used for the statistical comparison of year-by-year medical events and that provides baseline prevalences from which unexpected consequences of the radiation exposure of persons from Rongelap and Utirik can be identified. . Unless otherwise specified, the term Rongelap, when referring to the high-exposure group, combines those who were on Rongelap and those who were on Ailingnae at the time of exposure. The Brookhaven Medical Program Under Public Law 95-134, the Departmentof Energy has a contract with the Brookhaven National Laboratory Medical Department to provide for diagnosis and treatment of radiation-related disease among the exposed populations of Rongelap and Utirik. Although considerable effort is spent on the care of acute and chronic illnessesof any etiology, a program is in place which is oriented toward the problems posed by their 1954 radiation exposure. The exposed population must be considered at increased risk for malignant disease (Wakabayashi et al. 1983), and chief among the responsibilities of an ongoing program is a cancer-related evaluation. There may be additional risks unrelated to malignancy. The current strategy of the medical program is outlined below. 1. Acancer-related examinationis provided, using as a guide the current recommendations we