The monotonic uniaxial tensile behaviour of hemp-fiber-reinforced high density polyethylene (HDPE) was investigated at different values of hemp fiber volume fraction (vf) and strain rate (
). A normalized stress–strain family of curves was generated. An exponential normalized monotonic model was developed. A general uniaxial monotonic model was developed from the normalized model to simulate the stress–strain relationship at different values of
and vf. A modified Harris mechanistic model and a linear model were proposed to incorporate the effect of vf and the absorbed moisture into the developed model.