Abstract: There is disclosed a new, useful and simple apparatus, and surgical method, for implantation of same, for selective control of evacuating the urinary bladder in mammals by electrical stimulation of the motor innervations of the bladder's detrusor urinae muscle. Contractions of this muscle occur by timed electrical pulses conducted by electrodes placed in the fluid of the sacral canal, to conduct electrical stimulus through the fluid in the sacral region of the spinal cord. Nerve roots located in this region of the sacral canal, and which innervate the bladder, are stimulated by the electricity conducted by the fluid, causing contraction of the bladder's detrusor muscle, and results in micturition. In preferred form, the apparatus may be used on paraplegic or quadriplegic humans and could be selectively controllable by a paraplegic human. The apparatus may also be used to evacuate the bladder in paraplegic mammals such as dogs and cats.