Hydatidosis is a zoonosis caused by the ingestion of Echinococcus granulosus eggs, released though the feces, from infected dogs to humans. Primary localization is mostly hepatic and/or pulmonary, whereas muscular involvement is very rare, even more so in muscular striated tissue. This is the report of a case of a primary intramuscular hydatid cyst in a 79-year-old woman who presented with a 3-year history of a painful lump in her proximal medial left thigh. The authors document the exceptional giant dimensions of the cyst, which have not previously been reported in a case of striated muscular hydatid disease.