This study focuses on structural properties of para-sexiphenyl (PSP) epitaxial thin films grown on freshly cleaved mica (001) substrates. The layers were prepared by hot wall epitaxy (HWE) technique resulting in highly ordered organic structures with a needle-like morphology on the substrates. X-ray diffraction (XRD) pole figure technique, transmission electron diffraction (TED) and atomic force microscopy were used to characterise the epitaxial growth. However, on not perfectly cleaved mica substrates the needle direction Can Change around 120degrees when the films arc grown on different terraces of mica (001) which are separated by cleavage steps. This behaviour can be referred to the properties of the monoclinic crystal structure of mica which is described in detail. (C) 2002 Elsevier Science B.V. All rights reserved.