The invention comprises self-lubricating polymer compositions that are especially useful in medical devices and valves and gaskets of medical devices. In a preferred embodiment, the polymer compositions comprise a thermosetting or thermoplastic silicone elastomer in combination with a lubricity enhancing polyfluoropolyether fluid or hydrocarbon-based synthetic oil. In other preferred embodiments, the polymer compositions contain only biocompatible components. The improved anti-friction properties of the self-lubricating polymers can be demonstrated over a course of insertion and withdrawal cycles, where conventional polymers have changing and mostly increasing force required for each insertion and withdrawal, while the polymer compositions of the invention remain stable.