Abstract: An aquatic treadmill comprising a base (10) affixed to the edge (1) of a swimming pool (2), externally to the area occupied by the respective body of water (3); a structural arm (20) articulated to the base (10), in order to be selectively angularly displaced, by an arm actuator (12), between an inoperative position, elevated and external to the area occupied by the body of water (3), and an operative position, in which it is downwardly projected, so as to have a free end penetrating into the body of water (3); a chassis (30) having an end articulated to a free end of the structural arm (20), in order to be selectively angularly displaced, by a chassis actuator (50), between an inoperative position, seated against the structural arm (20), and a substantially horizontal operative position; and a support frame (40) mounted to the chassis (30) and carrying a pair of end transversal rollers (47), around which an endless belt (41) is mounted.