Abstract The various contributions to the total energy of dysprosium metal are calculated for divalent and trivalent ionic states and for h.c.p. and f.c.c. crystallographic lattices. The difference in energy for the four possible structures are found to be at most 6 rydbergs per unit volume, which is within the error bounds of the calculation. The terms involving the ionic properties favour the divalent state. The Ewald energy and the band structure energy favour the trivalent h.c.p. lattice.