Hydatid echinococcosis is preferentially localized in the liver. Muscular localization of hydatid cyst is an uncommon event. Symptoms are often discrete. Diagnosis is confirmed by the imaging: ultrasonography and/or magnetic resonance imaging, thus avoiding any untimely gesture. The treatment is surgical. The authors report a case of primary and isolated localization of a muscular hydatid cyst of the thigh in a sport woman revealed by cruralgia.