We have grown GaN films on LiGaO2 (LGO) (0 0 1) substrates by pulsed laser deposition (PLD) for the first time and investigated their structural properties using generalized grazing incidence-angle X-ray diffraction. By the use of PLD, we can grow high quality hexagonal GaN on LGO epitaxially without the use of any buffer layers, which is important to take advantage of the nearly lattice matched substrate. It has been shown that thin GaN films grown on LGO substrates are compressed in the lateral directions and that the lattice constant of GaN in the LGO [12 0] direction is slightly larger than that in the LGO [0 10] direction. This anisotropy is probably related to the crystal orientation dependence of the thermal contraction rate for LGO during the cooling down from the growth temperature. (C) 2003 Elsevier B.V. All rights reserved.