A possible optimal epitaxial relationship between the beta-FeSi2 film and a Si substrate was determined using the Delta g parallelism rule and a CCSL model. The predicted interface exhibits a good lattice matching, containing a secondary invariant line lying in an irrational orientation of [-2 -2.9 2.9](Si). The corresponding interface (-2.9 1 -1)(Si), which defines the plane of the Si substrate, must contain steps. This interface may contain a set of the secondary edge dislocations with the Burgers vector of [0 1 0](beta)/2 in a spacing of 26 nm to accommodate the small (1.5%) misfit between [0 1 0](beta) and [0 - 1 - 1](Si). Since the overall interfacial misfit is small, a high-quality beta-FeSi2 film will be possibly obtained by epitaxial growth on the special stepped Si substrate. (c) 2005 Elsevier B.V. All rights reserved.