A system for cooling or warming at least one portion of a patient's body, comprising: (a) an esophageal heat transfer device (200; 300) including: (i) a plurality of lumens (224, 226; 320, 322; 406, 408; 510, 512), a heat transfer medium supply tube lumen (224; 320; 406; 510) of a heat transfer medium supply tube (218; 310; 402; 502; 608) and a heat transfer medium return tube lumen (226; 322; 408; 512) of a heat transfer medium return tube (222; 312; 404; 504; 610), configured to provide a fluid path for flow of a heat transfer medium; (ii) a proximal end (204; 302) including a heat transfer medium input port (120; 208; 308; 414) and a heat transfer medium output port (122; 210; 314; 416); (iii) a distal end (202; 306) configured for insertion into an esophagus of a patient; (iv) at least one semi-rigid tube (206; 304) extending between said proximal end (204; 302) and said distal end (202; 306); said at least one semi-rigid tube (206; 304) defining said heat transfer medium supply tube lumen (224; 320; 406; 510) and said heat transfer medium return tube lumen (226; 322; 408; 512); (v) a heat transfer region configured for contacting esophageal epithelium of a patient; (b) a supply line connected to said input port (120; 208; 308; 414); and (c) a return line connected to said output port (122; 210; 314; 416); characterized in that said heat transfer medium return tube (222; 312; 404; 504; 610) is positioned within said heat transfer medium supply tube (218; 310; 402; 502; 608); and said heat transfer region has a surface area of at least about 100 cm 2; wherein said esophageal heat transfer device (200; 300) is capable of cooling a mass at a rate of about 350 kJ/hr to about 530 kJ/hr; and wherein said esophageal heat transfer device (200; 300) is a non balloon-type esophageal heat transfer device. (a) an esophageal heat transfer device (200; 300) including: (i) a plurality of lumens (224, 226; 320, 322; 406, 408; 510, 512), a heat transfer medium supply tube lumen (224; 320; 406; 510) of a heat transfer medium supply tube (218; 310; 402; 502; 608) and a heat transfer medium return tube lumen (226; 322; 408; 512) of a heat transfer medium return tube (222; 312; 404; 504; 610), configured to provide a fluid path for flow of a heat transfer medium; (ii) a proximal end (204; 302) including a heat transfer medium input port (120; 208; 308; 414) and a heat transfer medium output port (122; 210; 314; 416); (iii) a distal end (202; 306) configured for insertion into an esophagus of a patient; (iv) at least one semi-rigid tube (206; 304) extending between said proximal end (204; 302) and said distal end (202; 306); said at least one semi-rigid tube (206; 304) defining said heat transfer medium supply tube lumen (224; 320; 406; 510) and said heat transfer medium return tube lumen (226; 322; 408; 512); (v) a heat transfer region configured for contacting esophageal epithelium of a patient; (i) a plurality of lumens (224, 226; 320, 322; 406, 408; 510, 512), a heat transfer medium supply tube lumen (224; 320; 406; 510) of a heat transfer medium supply tube (218; 310; 402; 502; 608) and a heat transfer medium return tube lumen (226; 322; 408; 512) of a heat transfer medium return tube (222; 312; 404; 504; 610), configured to provide a fluid path for flow of a heat transfer medium; (ii) a proximal end (204; 302) including a heat transfer medium input port (120; 208; 308; 414) and a heat transfer medium output port (122; 210; 314; 416); (iii) a distal end (202; 306) configured for insertion into an esophagus of a patient; (iv) at least one semi-rigid tube (206; 304) extending between said proximal end (204; 302) and said distal end (202; 306); said at least one semi-rigid tube (206; 304) defining said heat transfer medium supply tube lumen (224; 320; 406; 510) and said heat transfer medium return tube lumen (226; 322; 408; 512); (v) a heat transfer region configured for contacting esophageal epithelium of a patient; (b) a supply line connected to said input port (120; 208; 308; 414); and (c) a return line connected to said output port (122; 210; 314; 416);