Some mechanical properties of five varieties of Iranian pistachio nut and its kernel (namely: Akbari, Badami, Kalle-Ghuchi, Momtaz and O'hadi) were determined. These properties include rupture force, deformation and rupture energy. Samples at various moisture contents were compressed along the X, Y- and Z-axes. The X-axis was considered the loading axis through the length dimension, while the Y-axis was the transverse axis containing the minor dimension (width) at right angles to the X-axis, and Z-axis was assumed the transverse axis containing the minimum dimension (thickness). The results showed that rupture force, deformation and rupture energy values decrease with increasing moisture content. The maximum rupture force, deformation and rupture energy values at all moisture levels as well as for all varieties were obtained for pistachio nut loaded along the X-axis. Compression along the Y-axis required less compressive force among the other two compression axes to extract the kernels. (C) 2009 Elsevier Ltd. All rights reserved.