The spontaneous rupture of neobladder is an extremely rare entity of which there only exists one formerly reported case in the world literature. It is far more common after enterocystoplasty for augmentation (19 reported cases). We describe here the spontaneous rupture of a neobladder 8 months after performing cystectomy and bladder replacement by an enterocystoplasty in order to treat a bladder carcinoma. In this case the patient showed symptoms and signs of acute peritonitis. The diagnosis was carried out using a cystogram and the treatment consisted of a laparotomy with closure of the perforation and drainage of the peritoneal cavity.