Fingernails from several sources were studied to determine elemental compositions. The common elements were found to be H, C, N, O, Ca and Fe. The elements Si, Bi, S, Mo, Ti, Zn, Pb, P and Nd were found on some of the nails; these are considered to result from environmental contamination, food and water intake. The compositions of H, C, N and O correlate with those in the hemoglobin molecule and, they do not vary significantly with time. This suggests that they are associated with dead blood cells. The other common elements, such as Ca and Fe, show variations in composition with time, probably because their amount in the body is determined by food and water intake. Fingernails from female sources have a higher concentration of Ca than those from male sources. Also, the concentration of Ca is generally higher on the outer than the inner surface of the nail, probably to provide a stronger bony structure and mechanical strength on the outside.