A dialysis catheter having a first portion having a first diameter, an elongated distal portion having a second diameter smaller than the first diameter, and a transition portion between the first portion and distal portion. The first portion includes first and second independent longitudinally extending blood withdrawal lumens and the transition portion has first and second opened areas separated by a rib, the first opened area forming a first terminal opening for the first withdrawal lumen and the second opened area forming a second terminal opening for the second withdrawal lumen. A longitudinally extending blood delivery lumen configured to deliver blood terminates in a delivery opening in the distal portion of the catheter.
