The role of the hypogastric nerves in the activity of cat's bladder was studied by means of nerve stimulation as well as exploration of the pattern of afferent impulses obtained from the same nerve.The results were as follows:1) Section of the hypogastric nerve resulted in lengthening of the period of spontaneous rhythmic contraction of the bladder in case of high intravesical pressure, while shortening of the period in case of low intravesical pressure.2) Stimulation given to the peripheral cut-end of the hypogastric nerve developed a brief contraction of the bladder which was followed by a marked relaxation. These characteristic phenomenon did not occur when the pelvic nerve and/or the inferior mesenteric ganglion was cut prior to the examination.3) The effect of stimulation of the peripheral cut-end showed no significant difference as compared with the effect of the central cut-end of the nerve.4) Autonomic reflex changes such as a rise of blood pressure and a change of respiratory pattern were obtained when stimulation was applied to the central cut-end. Such change, however, was not seen when the peripheral cut-end was stimulated.5) Hypogastric afferent impulses evoked by increase of intravesical pressure were considered to be two different groups. The first group comprised of impulses which were supposed to carry painful sensation without bearing any relation to mechanism of micturition. This type of impulses was observed only when the bladder was distended maximally and its adaptation was uaually very slow. The second group comparised of impulses which were induced along with gradual rise of the intravesical pressure.Summarising the above results of experiments, it may be concluded that:1) The hypogastric nerve appears to inhibit the activity of the bladder;2) Dr. Sokownin's finding is not acceptable. He clearly stated that there was an axon reflex by way of the inferior mesenteric ganglion;3) The fact that centripetal stimulation of the hypogastric nerve brings about autonomic reflex changes suggests that the bladder activity, more specifically, its relaxation seems to be more closely related to the reflex micturition center located in the medulla oblongata rather than the influence of the hypogastric nerve;4) Afferent impulses passing through the hypogastric nerve seems to be the evidence of transmission of the painful sensation. It may well be understood that the change of the intravesical pressure is conducted through the same pathway.