An expandable transluminal access sheath adapted for providing minimally invasive access to body lumens or cavities, comprising: an elongate sheath tube comprising: a distal region, which is expandable from a first cross-sectional profile to a second, greater cross-sectional profile in response to pressure applied therein; a proximal region; a transition zone comprising chevrons or serrations between said proximal region and said distal region, wherein the transition zone provides a smooth transition between said proximal region and said distal region when said distal region is in said first cross-sectional profile; and a through lumen extending through the distal region, the proximal region, and the transition zone, wherein said lumen forms a path of substantially uniform internal size when said distal region has been expanded to said second, greater cross-sectional profile; a sheath hub affixed to the proximal end of the proximal region of said elongate sheath tube, said hub adapted to form an internal lumen to facilitate the passage of instrumentation; and a balloon dilator within said elongate sheath tube and a guidewire lumen within the balloon dilator, the balloon dilator capable of radially expanding said distal region of said elongate sheath tube from said first cross-sectional profile to said second, greater cross-sectional profile; characterized by said distal region comprising a composite structure, said composite structure being folded in one or more longitudinal creases when said distal region is in said first cross-sectional profile, said composite structure comprising an inner surface, an outer surface, and a malleable reinforcement embedded between the inner surface and the outer surface of the distal sheath tubing, the malleable reinforcement maintaining the distal sheath tubing in its folded first cross-sectional profile by exerting a force that exceeds any forces imparted by the distal sheath tubing, and a dilator hub affixed to the proximal end of said dilator, the dilator hub releasably affixed to said sheath hub. an elongate sheath tube comprising: a distal region, which is expandable from a first cross-sectional profile to a second, greater cross-sectional profile in response to pressure applied therein; a proximal region; a transition zone comprising chevrons or serrations between said proximal region and said distal region, wherein the transition zone provides a smooth transition between said proximal region and said distal region when said distal region is in said first cross-sectional profile; and a through lumen extending through the distal region, the proximal region, and the transition zone, wherein said lumen forms a path of substantially uniform internal size when said distal region has been expanded to said second, greater cross-sectional profile; a distal region, which is expandable from a first cross-sectional profile to a second, greater cross-sectional profile in response to pressure applied therein; a proximal region; a transition zone comprising chevrons or serrations between said proximal region and said distal region, wherein the transition zone provides a smooth transition between said proximal region and said distal region when said distal region is in said first cross-sectional profile; and a through lumen extending through the distal region, the proximal region, and the transition zone, wherein said lumen forms a path of substantially uniform internal size when said distal region has been expanded to said second, greater cross-sectional profile; a sheath hub affixed to the proximal end of the proximal region of said elongate sheath tube, said hub adapted to form an internal lumen to facilitate the passage of instrumentation; and a balloon dilator within said elongate sheath tube and a guidewire lumen within the balloon dilator, the balloon dilator capable of radially expanding said distal region of said elongate sheath tube from said first cross-sectional profile to said second, greater cross-sectional profile; characterized by said distal region comprising a composite structure, said composite structure being folded in one or more longitudinal creases when said distal region is in said first cross-sectional profile, said composite structure comprising an inner surface, an outer surface, and a malleable reinforcement embedded between the inner surface and the outer surface of the distal sheath tubing, the malleable reinforcement maintaining the distal sheath tubing in its folded first cross-sectional profile by exerting a force that exceeds any forces imparted by the distal sheath tubing, and a dilator hub affixed to the proximal end of said dilator, the dilator hub releasably affixed to said sheath hub.