An orthotopic artificial bladder endoprosthesis comprises a casing (2) made of a PGA fiber fabric; said casing (2) having two first connectors (3) for the connection with the ureters of a patient and a second connector (4) for the connection with the urethra of a patient; a support element (5) being inserted in said casing (2); said support element (5) being switchable between an extended configuration, in which it supports and maintains in position the casing (2), and a retracted configuration.