The molecular beam epitaxy (MBE) growth of bcc Fe(110) thin films on an Al2O3(11-20) substrate using Mo(110) seed layers has been investigated. The growth was studied by reflection high energy electron diffraction (RHEED) in reciprocal space as well as by scanning tunneling microscopy in real space. The relative orientation between the lattices of the Fe(110) layer and the Al2O3(11-20) substrate has been identified and has enabled the construction of a model of the in-plane atomic arrangements. Side reflections found in RHEED patterns indicate the formation of ordered relaxation lines along the [100] direction of the Fe(110). © 2001 Elsevier Science B.V. All rights reserved.