Lattice parameters of the bcc and hcp phases of iron have been determined as a function of pressure up to 300 kbar at 23°±3°C by means of x‐ray diffraction techniques. Thec/aratio for hcp iron has been determined to be 1.603±0.001 at pressures between 80 and 300 kbar and is independent of pressure. Based upon the extrapolation of the high‐pressure data using an exponential form of the Murnaghan equation of state, the volume of hcp iron at zero pressure is 6.72±0.06 cm3/mole. The volume change for the bcc‐hcp transformation at 130 kbar is −0.34±0.01 cm3/mole. This value satisfies the triple point conditions for the bcc‐hcp‐fcc triple point when published values for the other phase transformations are used.