The　nonlinear　pulsatile　blood　flow　in　S-shaped　curved　arteries　was　studied　with　finite　element　method.　Numerical　simulations　for　flows　in　two　models　of　S-shaped　curved　arteries　with　different　diameters　and　under　the　same　boundary　conditions　were　performed.　The　temporal　and　spatial　distributions　of　hemodynamic　variables　during　the　cardiac　cycle　such　as　velocity　field,　secondary　flow,　pressure,　and　wall　shear　stresses　in　the　arteries　were　analyzed.　Results　of　numerical　simulations　showed　that　the　secondary　flow　in　the　larger　S-shaped　curved　artery　is　more　complex　than　that　in　the　smaller　one;　stronger　eddy　flow　occurred　in　the　inner　bends　of　curved　arteries;　pressure　and　wall　shear　stresses　changed　violently　in　the　curved　arteries,　especially　in　the　larger　model.　These　hemodynamic　variables　in　curved　arteries　will　cause　important　effects　on　the　function　of　arterial　endothelium　in　the　region.　For　instance,　they　may　lead　to　the　proliferation　of　smooth　muscle　cells　and　the　thickening　of　the　intima,　and　cardiovascular　diseases　such　as　atherosclerosis　may　develop　in　such　regions.　Due　to　having　the　special　blood　flow　characteristics　in　the　S-shaped　arteries,　it　is　worthwhile　to　study　flow　in　this　kind　of　curved　artery.　The　comprehensive　theoretical　foundation　showed　in　the　present　study　can　be　extended　to　approach　problems　of　nonlinear　pulsatile　flow　in　curved　arteries　with　more　complex　geometrical　shape.　(C)　2004　IPEM.　Published　by　Elsevier　Ltd.　All　rights　reserved.