Copolymerizations of propene and buta-1,3-diene performed in the presence of rac-[CH2(3-tert-butyl-1-indenyl)(2)]ZrCl2 and methylaluminoxane (MAO) have been investigated. Buta-1,3-diene gives prevailingly primary coordination to the metal, producing overall 1,2 units. Cyclopropane and cyclopentane rings, although in low amounts, are also obtained. The presence of butadiene would be responsible for some regioirregular 2,1-inserted propene units, which at high temperatures give rearrangement to 3,1 units.