In　practice,　concrete-filled　steel　tubes　(CFST)　are　often　subjected　to　torsion.　To　date,　such　a　problem　however　has　not　been　addressed　satisfactorily　by　design　codes.　The　present　study　is　thus　an　attempt　to　study　the　torsional　behaviours　of　concrete-filled　thin-walled　steel　tubes.　ABAQUS　software　is　used　in　this　paper　for　the　finite　element　analysis　(FEA)　of　CFST　subjected　to　pure　torsion.　A　comparison　of　results　calculated　using　this　modelling　shows　good　agreement　with　test　results.　The　FEA　modelling　was　used　to　investigate　the　influence　of　important　parameters　that　determine　the　ultimate　torsional　strength　of　the　composite　sections.　The　parametric　studies　provide　information　for　the　development　of　formulae　to　calculate　the　ultimate　torsional　strength,　as　well　as　the　torsional　moment　versus　torsional　strain　curves　of　the　composite　sections.　(c)　2007　Elsevier　Ltd.　All　rights　reserved.