We report a case of right-sided iatrogenic Horner’s syndrome developed after surgical treatment for pulmonary hydatid cyst. This occurred in a 10 year old girl who had been diagnosed as having a ruptured lung hydatid cyst on the basis of clinical, radiological, serological, histopathological and perioperative ﬁ ndings. The patient underwent right thoracotomy and the cystotomy-capitonnage for the cyst. Right upper lid ptosis, right miosis and anisocoria were recognized on the ﬁ rst postoperative day. Findings of Horner’s syndrome were ameliorated completely at the 6th month. In conclusion, iatrogenic transient Horner’s syndrome may develop after surgery for pulmonary hydatid cyst, especially if the cyst is located at the lung apex.