Washing of the supporting frames (10) of units (1) for transporting live poultry from the breeding farm to the slaughterhouse is carried out, following upon extraction of the drawer-type cages (2) containing the poultry, after positioning the supporting frame (10) in a condition where it is rotated through 90o with respect to the transport configuration. Washing is carried out via a network of tubes and spray nozzles (14) that can be displaced vertically from a raised, inoperative, position to a lowered, washing, position, where said network (14) sets itself around the rotated supporting frame (10). After the supporting frame (10) has been washed, it is repositioned in the transport configuration.
