Abstract: A catheter valve including a housing engaging at least a portion of a tubular member is provided. The tubular member having distal and proximal open ends defining a flow-through passage therebetween, the tubular member further having a proximal portion of a deformable and therefore twistable structure and a distal portion of a more rigid structure, the proximal portion being partially and circumferencially attached to an inner surface of the housing, wherein dimensions of the housing, of the proximal portion and of the distal portion are selected such that when the distal portion is rotated, the proximal portion is twisted so as to block passage of fluid through the tubular member and therefore through the catheter valve and the distal portion is secured by the housing so as to prevent self untwisting of the proximal portion.