Zirconocene complexes carrying substituents at various positions of their ring-bridged ligand frameworks were studied as catalysts for methylalumoxane-activated propene polymerization. Effects of different substitution patterns on catalyst activities and on chain lengths and stereo- and regio-regularities of the polymers produced are correlated with geometrical features of the complexes, e.g. with parameters describing their structural rigidity or the aperture and obliquity of their coordination gaps.