In this paper we describe an application of the sparse field method for solving level set equations in 3D anisotropic wet etching of silicon with potassium hydroxide (KOH). Angular dependence of the silicon etching rate is determined on the basis of the silicon crystal symmetry properties. Some examples illustrating developed methodology are given. The obtained results show that level set method can be used as an effective tool for wet etching process modelling. (C) 2009 Elsevier B.V. All rights reserved.