The paper describes a series of material/structural property tests on pultruded GFRP (glass fibre reinforced polymer) circular cross-section tubes used in guardrails. The tests enabled the elastic flexural and shear moduli of the tubes and the rotational stiffness of the post-base connections to be quantified. This information was then used to set up ANSYS FE (finite element) models of the guardrails using cubic beam elements and revolute joints to simulate the out-of-plane deflections of a two-bay plane guardrail loaded at the top of the centre-post and the mid-bays of the handrail. Load tests were carried on a full-scale guardrail in order to demonstrate that it complied with the load and deflection requirements given in the most recent design standard for guardrails. Thereafter, the ANSYS FE model deflection predictions were compared with those recorded during the load tests on the guardrail. It was shown, that including revolute joints in the model gave deflections that were, in the worst instances, within 15% of the values recorded in the physical tests.