Average tissue compositions have been derived for seven groups of soft tissues found in "Reference Man". The analyses took into account some 40 soft tissues comprising the adult human. Different groups of soft tissues were selected to provide average tissue compositions of practical value in radiation dosimetry. In addition, as more reliable skeletal tissue data are now available, an updated tabulation is given of average bone formulations. Elemental compositions and mass and electron densities are tabulated for all of the derived systems.