Medical devices and methods for making and using medical devices are disclosed. An example medical device may include a guide extension catheter. The guide extension catheter may include a proximal tubular member having a lumen defined therein. A distal tubular member may be attached to the proximal tubular member. The proximal tubular member may have an outer diameter. The distal tubular member may have an inner diameter. The inner diameter of the distal tubular member may be greater than the outer diameter of the proximal tubular member. A stiffening member may be slidably disposed within the proximal tubular member.
