Neutron bombardment (neutron flux, 3 X 10(12) neutrons/cm2/s) of prepared iron tablets containing glycine-iron or iron alone was performed to prepare radioactive tablets to assess the effects of glycine on iron absorption from tableted formulations. No interfering isotopes of sufficient quantity were generated during neutron activation of the iron tablets. Cobalt-60 was the major trace mineral detected and accounted for only 1.3% of the total activity. There may have been trace amounts of zinc-65 or chromium-51 present, but they were not detectable above background radioactivity in the final tablet produced. Iron-59 represented greater than 98% of the radioactivity present in the tablets used in the study. Glycine-containing iron tablets produced dramatically higher amounts of iron in blood and tissues of rabbits (p less than 0.05) than did the same tablet formulations without glycine. The area under the iron blood concentration-time curve over 4 h increased by 67% with glycine added to the formulation over control iron tablets. Iron concentrations in tissues 4 h after iron administration was in the order of blood greater than liver greater than heart greater than kidney greater than muscle.