Abstract: A catheter has a shaft with a water-resistant protective covering along its length. The covering protects the catheter shaft, i.e., catheter body and tip section, from the elements of in vivo conditions, i.e., blood and other body fluids, and reduces softening of the catheter over time. The covering also adds a lubricious surface to increase the mobility of the catheter. However, the protective covering does not substantially affect the mechanical properties of the catheter. The covering extends over at least about 50% of the shaft. The covering has a thickness less than about 0.004 inch and is formed of a material having a water vapor transmission rate of less than about 9.0 g-mil/100 in2-24 hr at about 90% relative humidity and about 37° C.