The ring-opening metathesis polymerization of a series of cycloalkenes initiated using well defined Schrock-type initiators is described. The products have been characterized by gel permeation chromatography, nuclear magnetic resonance and differential scanning calorimetry. The influence of initiator, reaction conditions and monomer structure is analysed in detail. The detailed microstructures of the polymers can be deduced from the C-13 nuclear magnetic resonance spectra and apparent anomalies are accommodated in terms of the gamma-gauche effect established by Tonelli.