The se~um cholesterol level in this report were obtained as a part of the Health and Nutri­ tion Examination Survey (HANES). HANES is a program of the National Center for Health Sta­ tistics in which measures of nutritional status are collected for a scientifically designed sample representative of the civilian, noninstitutionaIized population of the United States in a broad range ~fages, 1-74 years.1 � Field data collection operations for the first HANES survey were started in ApriI 1971 and completed in June 1974. Of the 28,043 persons aged 1-74 years who were selected in the nation­ al probability sample to represent the 194 milIion persons in that age group in the civiIian noninstitutionalized population, 20,749, or 74 percent, were examined. When adjustments were made for the differential sampling ratios used for the effect of oversampling among the poor, . preschool children, women of childbearing age, and the elderly, this corresponds to an effective response rate of 75 percent. There were 13,645 people ages 18-74 years on whom serum choles­ terol level determinations were made. Selected “ from the nationzd probability sample of 19,572, these individuals represented the 128 million of that age group in the population. This is an un­ adjusted response rate of 70 percent and an ef­ fective adjusted response rate of 70 percent. Detailed estimates of the distribution of serum cho­ lesterol levels wiIl be described and analyzed in a forthcoming report in Series 11 Z of Vital and Health Statistics. Selected data and findings