This paper presents an experimental investigation on the flexural behaviour of ultra-high strength concrete filled steel tubes with concrete compressive strength up to 180MPa. Both hot finished hollow sections with S355 steel and welded steel box sections with S700 plates were used to prepare the test specimens. The composite cross-section configurations consist of single-tube and double-tube sections infilled with ultra high strength concrete. Test results obtained include load-deflection plots, ultimate loads and failure modes. The ultimate loads from tests were compared with Eurocode 4 predictions by extending its limitations on the material strengths to high strength steel S700 and ultra-high strength concrete C180. The paper recommends that Eurocde 4 method can be used to predict the ultimate resistance of ultra-high strength concrete filled steel tubes with high strength materials, and they are feasible for use in high-rise buildings with reduced structural member size.