This　study　experimentally　and　numerically　investigates　the　flexural　behavior　of　high-strength　rectangular　concrete-filled　steel　tube　(CFST)　members.　An　experimental　database　including　30　flexural　tests　on　high-strength　rectangular　CFST　members　was　compiled,　and　gaps　in　the　existing　research　were　identified.　To　address　these　gaps,　a　total　of　14　specimens　were　tested,　considering　the　effect　of　tube　thickness,　compressive　strength　of　concrete,　yield　stress　of　steel,　and　tube　height.　Detailed　finite-element　models　were　also　developed　and　benchmarked　for　parametric　studies.　Results　from　the　tests　and　finite-element　analyses　indicated　the　following:　(1)　the　flexural　strength　increased　with　the　increasing　tube　thickness,　yield　stress　of　steel,　tube　height,　and　tube　width,　while　the　effect　of　the　compressive　strength　of　concrete　was　minor;　(2)　the　flexural　stiffness　increased　with　the　increasing　tube　thickness,　tube　height,　and　tube　width,　while　the　effect　of　the　yield　stress　of　steel　and　compressive　strength　of　concrete　was　minor;　and　(3)　high-strength　CFST　members,　especially　those　with　high-strength　steel　tubes,　had　lower　ductility　compared　with　conventional-strength　CFST　members.　Experimental　and　numerical　results　were　also　used　to　evaluate　the　applicability　of　current　design　provisions　(i.e.,　AISC　360-16,　GB　50936-2014,　Eurocode　4,　and　the　AIJ)　for　estimating　the　flexural　strength　and　stiffness.　The　evaluation　showed　that　AISC　360-16　reasonably　estimated　the　flexural　strength,　while　AIJ　provided　the　most　accurate　estimation　of　the　service-level　flexural　stiffness.　©　2021　American　Society　of　Civil　Engineers.