ansa-Zirconocene complexes have been studied by Three-Dimensional Quantitative Structure-Activity Relationship (3D-QSAR). Using the comparative molecular field analysis (CoMFA) method, the experimental results obtained for catalytic activity and polymer molecular weight have been successfully correlated with the steric and electrostatic 3D structural descriptors, which were calculated by density functional theory (DIFT) methods. (c) 2007 Elsevier Ltd. All rights reserved.