Some geometrical properties of five major commercial Iranian pistachio varieties were evaluated as a function of moisture content. The moisture content of five varieties ranged from their harvest moisture content to a minimum of about 3-5% for nuts and 4-6% for kernels. The results showed that the length, width, height, sphericity, surface area, geometric and arithmetic mean diameters of pistachio nuts decreased and the shell splitting increased with decreasing moisture content. Corresponding values for pistachio kernels gave similar results. The relationships between the geometrical properties and moisture content of pistachio nuts and their kernels were obtained linearly as represented by regression equations. (c) 2006 Elsevier Ltd. All rights reserved.