A reinforced multi-lumen catheter and method of manufacturing the same. An assembly for manufacturing the multi-lumen catheter includes a catheter body substrate including a septum, one or more mandrels, a reinforcing element and one or more sleeves. The septum may have a distal region with a cross-sectional thickness greater than that of a proximal region. The septum can be separately formed. The septum can be split along a length of the distal region. The reinforcing element can be positioned over at least a proximal region of the catheter body substrate.