A variable hemostasis valve, comprising: a valve body having a proximal housing component (116, 117) that is rotatable relative to a distal housing component (118, 119); and a tubular seal element defining a fluid passageway between a proximal end and a distal end thereof, the tubular seal element being positioned within the valve body such that the fluid passageway forms a midsection of a lumen (126, 138) through the valve body, wherein the proximal end of the tubular seal element is operably coupled to the proximal housing component (116, 117) and the distal end of the tubular seal element is operably coupled to the distal housing component (118, 119); wherein upon the proximal housing component (116, 117) being rotated relative to the distal housing component (118, 119), the tubular seal element may be selectively twisted between an open position that permits fluid flow through the passageway and a closed position that restricts fluid flow through the passageway; wherein the valve body includes a proximal flange portion forming a proximal segment of the valve body lumen and a distal flange portion forming a distal segment of the valve body lumen; wherein the tubular seal element is disposed between the proximal flange portion and the distal flange portion such that the fluid passageway thereof is in fluid communication with the respective proximal and distal segments (138, 12) of the valve body lumen; and wherein the proximal housing component (116, 117) includes first and second portions that are securable together to surround and clamp the proximal flange portion and a first segment of the tubular seal element therebetween and wherein the distal housing component (118, 119) includes first and second portions that are securable together to surround and clamp the distal flange portion and a second segment of the tubular seal element therebetween; wherein the tubular seal element is a hollow cylindrical tube. a valve body having a proximal housing component (116, 117) that is rotatable relative to a distal housing component (118, 119); and a tubular seal element defining a fluid passageway between a proximal end and a distal end thereof, the tubular seal element being positioned within the valve body such that the fluid passageway forms a midsection of a lumen (126, 138) through the valve body, wherein the proximal end of the tubular seal element is operably coupled to the proximal housing component (116, 117) and the distal end of the tubular seal element is operably coupled to the distal housing component (118, 119); wherein upon the proximal housing component (116, 117) being rotated relative to the distal housing component (118, 119), the tubular seal element may be selectively twisted between an open position that permits fluid flow through the passageway and a closed position that restricts fluid flow through the passageway; wherein the valve body includes a proximal flange portion forming a proximal segment of the valve body lumen and a distal flange portion forming a distal segment of the valve body lumen; wherein the tubular seal element is disposed between the proximal flange portion and the distal flange portion such that the fluid passageway thereof is in fluid communication with the respective proximal and distal segments (138, 12) of the valve body lumen; and wherein the proximal housing component (116, 117) includes first and second portions that are securable together to surround and clamp the proximal flange portion and a first segment of the tubular seal element therebetween and wherein the distal housing component (118, 119) includes first and second portions that are securable together to surround and clamp the distal flange portion and a second segment of the tubular seal element therebetween; wherein the tubular seal element is a hollow cylindrical tube.