Iron was deposited in high vacuum (10−7 to 10−8torr) onto (001) nickel surfaces prepared inside the vacuum chamber. It was found that continuous iron films were formed early in film growth, and that these films were f.c.c. and strained to match the nickel lattice. When the thickness of the iron deposits reached 15±3 Å small elongated nuclei of b.c.c. iron appeared. Those nuclei were in the orientations described by Pitsch (1959) and grew in size as film growth proceeded. Misfit dislocations were not observed at any stage in the growth of 150±204 Å iron films. It is suggested that they were absent because much of the misfit between f.c.c. iron and nickel was accommodated by the lattice distortion associated with the formation of b.c.c. grains in the Pitsch orientation. © 1969 Taylor & Francis Group, LLC.