THE effects of the dystrophic process upon muscle function are of continued interest. Dystrophic mouse muscle has been found to exhibit multiple action potentials, spontaneously, as well as in response to a single stimulus to its nerve1,2; d-tubocurarine or sustained, periodic single shock stimulation shortens the after-discharges1. Heightened muscle responsiveness and excitability to dual shocks also develop1. In addition, excised dystrophic muscle is less fatiguable and maintains a tetanus for a longer time than the normal3. It was felt that an investigation of neuromuscular fatiguo might help to further delineate and perhaps clarify some of these phenomena.