Sclerosing encapsulating peritonitis (SEP) is a rare and little known pathological entity. It is a chronic fibro-inflammatory disease of the peritoneum, resulting in the formation of a thick fibrous membrane, which engages partially or totally the abdominal organs. Clinical and radiological signs make the diagnosis difficult to establish preoperatively. We present two original observations of SEP illustrating different clinical presentations, diagnostic and therapeutic means. His diagnosis requires a peritoneal biopsy. The treatment is not completely established. Surgical treatment is difficult, involving viscerolysis and multiple incisions of the fibrous membrane. Despite the current progress in therapeutic management, the prognosis remains pejorative, with significant mortality.