Prestressed steel trusses can offer efficient structural solutions for long span applications such as aircraft hangars, stadia and warehouses. In the current study, the tensile behaviour of prestressed steel elements, which comprise tubular steel members with internal prestressing cables, is investigated. The stability of the elements under prestress and the load–deformation response of the prestressed elements to the subsequent application of tensile loading are examined analytically, numerically and experimentally, with good correlation achieved between the three approaches. The benefits of prestressing, in terms of increased member strength and stiffness, are demonstrated, and optimal prestress levels are investigated.