The thermopower of pure iron and dilute iron-vanadium alloys (0-1.8 at.% V) has been measured in the temperature range 300-1750 K. The temperature dependence of the thermopower for the BCC phases above and below the FCC regime has been clearly established for the first time. The large differences between the BCC and FCC values reflect the difference in band structures, and the large value for the lattice indicates the presence of fine structure in the energy spectrum and hence a strong energy dependence of scattering.