Dead loading creep and constant strain rate yield experiments have been used to study the tensile creep behaviour of three grades of isotropic polyethylene. This has provided further evidence for the existence of two yield points in isotropic polyethylene. Two different models have been used to attempt to describe this behaviour. Although the results can be described by to both the two process model of Wilding and Ward and the co-operative jump model of Fotheringham and Cherry, it appears that the two process model provides a more convincing quantitative fit to the data.