Human iron metabolism has been extensively studied in the past twenty-five years with the radioisotopes iron⁵⁵ and iron⁵⁹. Before the availability of the whole body counter, however, iron absorption studies were performed by the indirect methods of fecal assay of unabsorbed radioiron, and estimation of red cell incorporation of absorbed tracer. The few long-term excretion studies performed required numerous assumptions, since human iron excretion was less well understood. Whole body counting provides a simple and accurate method of measuring the total body retention of administrative tracer iron⁵⁹, thus making absorption and subsequent excretion determinations possible with a single radioiron study. The energetic gamma emissions of iron⁵⁹ permit ready external detection with small quantities of isotope, Normal radioiron distribution is uniform throughout the circulating red cell mass and thus minimize geometry influences on the counting efficiency, 0nly the 45.1 day half-life of iron⁵⁹ limits long term iron turnover studies. Measurements of iron⁵⁹ absorption and long-term body turnover have been under way at Brookhaven National Laboratory for over two years. The present paper outlines some of the results of these studies, and discusses some implications of the method.