Abstract. In this study, the topics of grid generation and FEM applications are studied together following their natural synergy. We consider the following three grid generators: NETGEN, TetGen and Gmsh. The qualitative analysis is based on the range of the dihedral angles of the triangulation of a given domain. After that, the performance of two displacement decomposition (DD) preconditioners that exploit modified incomplete Cholesky factorization MIC(0) is studied in the case of FEM matrices arising from the discretization of the three-dimensional equations of elasticity on unstructured tetrahedral grids.