A first-order phase transition in the magnetization of Fe films, driven by an applied magnetic field, was first reported by Hathaway and Prinz . Further studies were performed on this phase transition using anisotropic magnetoresistance measurements by Riggs and Dahlberg . Here we report the extension of these studies to include temperatures between 77K and 293K. Emphasis is on a determination of the fourth-order and uniaxial anisotropy constants (K1 and Ku). It is shown that the temperature dependence of the anisotropy energies in these films varies with thickness, which may be useful in sorting out the origin and magnitude of different contributions to the total effective anisotropy. The present study suggests that similar studies of (110) iron on other substrates might contribute to achieving a better understanding of in-plane anisotropies in epitaxial films.