In this article, we report a rare case of hydatid cyst in the posterior aspect of the thigh of a 70-year-old lady from the endemic region (Yemen). She presented to the orthopedic clinic in King Abdulaziz University Hospital, Jeddah, KSA, complaining of a painless, gradually progressive swelling of the left posterior thigh. Diagnosis was reached by computed tomography scan and MRI of the left thigh, and confirmed with an ultrasound-guided fine needle aspiration. The cyst was treated with a wide excision and 3 months of albendazole. The primary intermuscular hydatid disease is a rare condition. Clinically, it presents as a painless slowly growing mass. Preoperative diagnosis is essential because cyst rupture and dissemination may lead to recurrence. The diagnosis can be obtained by computed tomography scan, MRI, and ultrasound. A fine needle aspiration may done to confirm the preoperative diagnosis. Combination of wide excision and chemotherapy in such cases is the recommended and curative treatment.