Hydatid disease is caused by Echinococcus granulosus parasite. It is an endemic disease;particularly in many Mediterranean countries. The liver and the lungs are most frequently involved. Bone involvement is reported in 1% - 2% of the cases and about 50% of those are seen in the spine. Herein we report a case of primary spinal extradural hydatid cyst that caused paraplegia due to compression of the dorsal spinal cord and was diagnosed initially as case of lumber prolapsed intervertebral disc. The cyst was only discovered when the patient had progressive paraplegia and the preoperative provisional diagnosis was posterior mediastinal neurogenic tumor causing destruction of the pedicle and lamina of the fifth thoracic vertebra. Fortunately, she regained near full power after surgical treatment of her spinal cyst.