In this research, modifying effects of some soybeans on the properties of an investment casting sprue wax (1397) have been studied. For this purpose, soybeans of Wilken-3480, NS-6, RHS-6592 and SGI-3308 varieties have been used as the additives. The effects of these soybeans on the surface roughness, solidification shrinkage, viscosity, hardness, tensile strength and wettability of B97 have been investigated. It has been conclusively shown that these soybeans improve the properties of B97 to such an extent that it converts into a pattern wax having properties superior to those of a commercial investment casting pattern wax (B140). (C) 2003 Elsevier Science Ltd. All rights reserved.