Human Echinococcus infection still remains an important health problem in endemic regions. Primary musculoskeletal Echinococcus infection is very rare without involving the thoracic and abdominal organs. There has been no reported case of intermuscular hydatid cyst in the very early ages of childhood. Here we report a case of a 4-year-old girl with a primary intermuscular hydatid cyst in the left thigh. It was localized between the adductor muscles and iliopsoas muscle. It was removed without destroying the cyst wall and there were no complications. Hydatid cyst should be considered especially in the endemic areas when evaluating cystic masses. Hydatid cyst can be treated by operation. (c) 2007 Elsevier Inc. All rights reserved.