Free radical homo- and copolymerisations of vinyl acetate and butyl acrylate were carried out in solution. Initial differences in data from homopolymerisation experiments lead us to investigate the influence of an eventual oxygen inhibition on the observed rate of polymerisation. A kinetic study at 70 degrees C was carried out both with and without a nitrogen purge. A decrease in the rate of polymerisation in the second instance was attributed to the presence of dissolved oxygen in the solution. Estimates of the apparent inhibition constant from different experiments are used to model both homopolymerisation and copolymerisation with vinyl acetate. The importance of taking this phenomenon into account during kinetic studies is demonstrated.