Several physical and nutritional properties of four hazelnut varieties (Palaz, Tombul, Cakildak, and Kara, which are major commercial Turkish hazelnut varieties) were determined and compared in terms of linear dimensions, mass, volume, sphericity, surface area, projected area, true and bulk densities, porosity, repose angle, shell ratio, terminal velocity, rupture force, static coefficient of friction of hazelnuts and crude protein, oil, crude fiber, energy, ash, dry matter, carbonhydrate and some minerals i.e. K, P, Ca, Mg, Na, Mn, Fe, Zn and Cu contents of samples. All the properties of hazelnuts and kernels that provide useful data to engineers in the design of processing machines were generally found to be statistically different in the four hazelnut varieties. These differences could be attributed to the individual characteristics of these varieties and environmental and growth conditions. (C) 2003 Elsevier Ltd. All rights reserved.