Hydatid disease is a parasitic infestation of humans and herbivorous animals, caused by Echinococcus granulosus. Dogs and some wild carnivores, such as foxes, are definitive hosts, harboring worms in their intestines. Musculoskeletal cysts represent 0.7 to 3% of the total number of cases of hydatidosis. Primary muscular hydatidosis without involvement of the thoracic or abdominal organs is extremely rare. Intramuscular infestation can mimic a soft tissue tumor resulting in inappropriate rupture of the cyst with the associated risks of anaphylaxis and dissemination to other organs. Preoperative evaluation is therefore essential to avoid life-threatening complications. We report the case of a 64-year-old patient presenting with a cystic swelling of the thigh admitted to the emergency department for a ruptured hydatid cyst. Surgical excision with complementary pharmacological treatment is necessary to obtain complete cure.