Hydatid disease is a parasitic infestation that is caused by Echinococcus granulosis. The liver is the most frequently involved organ (75%), followed by the lung (15%). The solitary retro-peritoneal localization is extremely rare, and its incidence is unknown. In our patient, the hydatid cyst was located intra-abdomen, retro-peritoneal, retro vesicular wall which makes this an interesting case.