The structure of Fe films thermally deposited on Cu(001) was analyzed using surface x-ray diffraction in the coverage range between 6 and 8 monolayers. Based on the analysis of crystal truncation rod data measured at 120 and 300 K, i.e., below and above transition temperatures reported for ferro- and antiferromagnetic ordering, no changes of the interlayer spacings larger than about ±0.015 Å are found. Within the Fe film these correspond to fcc Fe (1.78 Å), while the top-layer spacing is expanded by 3-5 % in agreement with previous low-energy electron diffraction studies. Lateral disorder of surface atoms as described by the Debye parameter indicates displacements of the top-layer positions up to 0.23 Å corresponding to zigzag displacements observed in the p2mg (2x1) superstructure. The inherent large penetration depth of the x rays also allowed the study of the structure and composition of the buried Fe/Cu interface. The data indicate Fe-Cu intermixing, where nearly 50