Propene has been polymerized with three different metallocene complexes : Me2Si(Ind)(2)ZrCl2 (I), Me2Si(BenzInd)(2)ZrCl2 (II), and Me2Si(MeBenzInd)(2)ZrCl2 (III) by using C-13-enriched cocatalyst MAO/Al((CH3)-C-13)(3). The stereochemical analysis of selectively C-13-enriched methyl chain end groups has shown that, while a moderate first step enantioselectivity is present with catalyst I, the bulky benzannelated substituents (catalysts II and III) lead to an almost total lack of steric control on the first monomer insertion. The methyl substitution in the a-position of cyclopentadienyl ring (catalyst III) does not seem to influence the choice of the face.