Embryonically, urinary organ has been closely related to the sexual organ, but no one has reported a systematic study of influences on the bladder function by sexual hormones. With ripe male rabbits, I experimented on the above systematic study by my original cystometric method.The Experiment was tried after or during the injection of different hormones, the dose of which was divided into three doses converted from human's therapeutic dose, and they were graded above normal (large), normal and less normal (small).The obtained results were as follow.(A) The Influences of different steroid hormones:I) Male hormones:(1) Extract of testis (Spermatin) and androgen (Enarmon) were not effective, but testosterone acetate (Enarmon-S) showed that effects of small and normal doses on the normal bladder were hyperactive, but effects of large doses were hypoactive.(2) Castration caused hypofunction and this influence was being made gradually clear during 1 month after the castration. Following 1 month after the castration, this influence was being stabilized.This influence was not recovered by the injection of androgen and extract of testis, but was recovered a little by the small or normal dose of testosterone acetate and much by the large dose of testosterone acetate.II) Female hormones:(1) The large dose of estrogen (Ovahormon benzoat) caused hypofunction a little and the normal or large dose of synthetic estrogenic substance (Estimon, Suron and Rohormon) caused marked hypofunction on the normal Bladder.By the large dose of estrogen, the hypofunctional influence on castrated bladder was not changed and with the normal or large dose of synthetic estrogenic substance, it was improved.(2) Extract of corpus luteum (Oophormon luteum) was not effective, but progestrone acetate (Synthetic Oophormon luteum) showed that its administration caused hyperfunction a little and its normal dose caused so much effect on the normal bladder also.By the extract of corpus luteum, the hypofunctional influence on the castrated bladder was unchanged and with the large dose of progesterone acetate, it was improved as the normal dose of testosteron acetate.(B) The influence of gonadotropic hormones:I) Extract of pituitary anterior lobe (Hypohorin) was not effective on the normall bladder.On the normal bladder, the large dose of the extract caused hyperfunction a little, but it caused hypofunction a little on the castrated bladder.II) Adrenal cortical hormones:Extract of adrenal cortex (Interenin) was not effective, but desoxycorticosterone acetate (Cortate) showed that its normal or large dose caused hyperfunction a little on the normal bladder and recovered the hypofunctional influence a little on the castrated bladder.