We studied the influence of nanoscale ZnO films deposited onto GaAs (001) on the process of GaAs epitaxial growth. We took into consideration the most important control parameters of molecular beam epitaxy, such as substrate temperature, As4/Ga effective flux ratio and growth rate and different thicknesses of ZnO films. We found that a ZnO film deposited on GaAs surface acts as a native GaAs oxide when the thickness of the film is being decreased, and can be removed thermally at a temperature of 620-630°C. We showed that it is possible to use nanoscale ZnO films with thickness ∼5 nm in order to create horizontal GaAs nanowires grown by a self-catalytic mechanism.