Hydatid cysts of the orbit are relatively rare lesions. They usually present as a tumoral exophthalmia but may have a pseudo-malignant appearance. Diagnosis is based essentially on a needle puncture during the initial stages of the operation after dissecting out the tumor, the liquid obtained having a typical spring-water appearance. Treatment is surgical but complete extirpation of the cyst is not attempted, the proligerous membrane being ablated after applying formation to the cyst cavity. The approach is neurosurgical for tumors of the retrobulbar cone, and by Rollet's subaponeurotic for other localizations. Systematic puncture during the initial operative stage on orbital tumors is suggested in countries where hydatid disease is endemic.