The sartorius muscle is a rare location of primary hydatid cyst. In this report, the clinical, pathologic, and radiologic features are discussed, with special emphasis on the pathologic and radiographic features. We report a case of hydatid cyst of the proximal thigh in an eight-year-old girl. Magnetic resonance (MR) images revealed muscular hydatid cyst in the sartorius muscle, with a striking appearance of daughter cysts. We did not find any visceral organ involvement. Wide excision was performed without destroying the cyst wall. Primary muscular hydatidosis should be kept in mind in the differential diagnosis of a cystic mass of a skeletal muscle.