1. The repetitive response of a nerve fiber was induced by applying constant currents to the nerve trunk or to a single nerve fiber treated with a 5 per cent NaCl solution.2. The relation between the voltage of the applied current and the response time is represented by a curve of an ordinary hyperbolic shape, though the latter is comparatively longer than that of normal make response.3. Particularly long intervals were often found between two successive impulses in a series of repetitive impulses, perhaps expressing conduction blocks.4. The relation of the logarithm of the applied voltage to the frequency between impulses was approximately represented by a straight line.5. The accommodation of the nerve fiber was decreased after application of a NaCl solution.6. The recovery process of the nerve fiber was retarded by application of a NaCl solution. The parallel relation between the recovery curve and the frequency of the repetitive response suggests that the recovery process may determine the frequency of the repetitive response.