A multitube catheter is provided. The assembly includes two or more tubes fused together to form one catheter tube shaft. Each tube has at least one lumen extending longitudinally through the catheter from its distal end to its proximal end. The tubes are fused together by use of heat and pressure. A distal end of the united catheter tube can be split to form a split tip, stepped tip, or a tapered tip. The proximal segment (non-fused portion) forms catheter extension legs.