BACKGROUND Hydatid cyst is a parasitic disease caused by echinococcus granoulosis. It is endemic in Mediterranean areas, south America, north Africa and Australia. The disease is most common in the liver and then in lung, the chest wall involvement by hydatid disease is a very rare condition. METHODS We present a case of chest wall mass in a 65-years old man, who intra operatively diagnosed as primary hydatid cyst. Cystectomy done and patient followed up for 2 months. CONCLUSIONS The diagnosis of echinococcus infection mainly depends on the clinical history of the patient, serologic tests, and diagnostic radiological findings. Operative procedures for chest wall hydatid disease are cystectomy, cystotomy, evacuation, and chest wall resection. CONCLUSIONS Chest wall hydatid disease should be considered in the differential diagnosis of chest wall masses even in a patient who has not been operated for hydatid disease.