A structural study of Fe ultrathin epitaxial films, grown at room temperature on Ni͑111͒, has been performed in the 1.5-18 ML coverage range by angle-scanned photoelectron diffraction. Both backscattering and forward-scattering energy regimes have been employed, in order to enhance the structural sensitivity at lower and higher film thicknesses, respectively. Modeling of the experimental data has been performed with multiple scattering calculations. We found indications that Fe atoms in the first layer occupy fcc hollow sites and stack with a pseudomorphic fcc structure up to 2 ML. Concerning the growth mode at these early stages, data suggest that a good substrate wetting and a sharp Fe/Ni interface take place. Between 3 and 6 ML, transition to a bcc͑110͒ phase develops. By quantitative R-factor analysis, we found that Nishiyama-Wassermann ͑NW͒ in-plane orientation of the bcc͑110͒ cell (͗001͘ bcc ʈ ͗11 0͘ fcc ) is favored over the Kurdjumov-Sachs (͗11 1͘ bcc ʈ ͗11 0͘ fcc ) orientation. The best-fit vertical interlayer distance between bcc͑110͒ planes is d NW ϭ2.11 Å ͑ϩ3.9% expansion͒ at 6 ML and relaxes to d NW ϭ2.05 Å ͑ϩ1.0%͒ at 18 ML, in agreement with the angular shift observed for the forward-focusing features. In the same coverage range, the angle between bcc͑110͒ surface basis vectors changes from 67.7°to 69.0°, corresponding to Ϫ1.7% and Ϫ1.0% contractions of the surface cell area, respectively.