Tubular structures have become increasingly popular for steel and aluminium construction, for economic and aesthetic reasons, yet member deterioration and fatigue-cracking of connections is often reported in the offshore industry, in the transportation and agricultural sectors, and with amusement rides.The suitability of such materials to rehabilitate tubular steel members and the structural behaviour of the resulting composite system were investigated experimentally. The programme was tailored primarily to the offshore industry and techniques associated with underwater repair methods. Employing awet-layup application method, the main focuswas on the static flexural performance of steel-FRP composite beams, with principal experimental parameters being the fibre and epoxy material types and the matrix curing conditions. Curing of the specimenswas performed both in air and in seawater, the latter simulating the condition for underwater application to offshore structures.The strengthening process was effective as all wrapped composite members exhibited improved structural performance compared to that of a bare tube. The current study has proven the feasibility of rehabilitating tubular steel members with advanced composite materials, underwater.