A uterine fistula is aseptically prepared in the rabbit by securing the cervical ends of the uteri, along with a sheath of vagina, through a stab incision in the lower ventral abdominal wall. Activity is recorded from such rabbits in the unanesthetized condition from one horn or from both simultaneously by an intrauterine balloon connected with a Brodie bellows through a water and air transmitting system. The method of making the balloons and bellows is described. Data are given on normal uterine activity of 4 rabbits for periods of from several days'' to 11 weeks'' duration. Progressive variations in the type of activity are described, but no explanation of them is offered. The animal preparation and method are critically discussed.