For many years magnesium oxide (MgO) played a key role in the research of buffer layers for high-temperature superconducting copper oxides. For buffer layers, not only the out-of-plane alignment has to be taken into account, but also the in-plane orientation, which is important. The goal of our experiments is to grow biaxially aligned layers, i.e. layers with both out-of-plane alignment and in-plane alignment. The biaxially aligned MgO layers are deposited by unbalanced magnetron sputtering on a non-textured substrate. By varying different deposition parameters (e.g. inclination angle, pressure, reactive gas flow, distance between target and substrate, etc.) it is possible to improve the biaxial alignment. MgO layers with a preferential [1 1 1] out-of-plane orientation and an in-plane alignment with a FWHM of 19.6degrees in phi and 7.8degrees in chi are observed. (C) 2004 Elsevier. B.V. All rights reserved.