Pancoast syndrome remains a rare presentation of pulmonary diseases. Even in endemic area of echinococcosis, lung's hydatid cyst is seldomly revealed by this syndrome. We report a case of a 38 year old male patient who presented to our department with neck and left superior limb pain associated with palmar muscle atrophy and Horner's syndrome. Radiological investigations suggested the diagnosis of hydatid cyst of the left lung apex which was confirmed by surgical excision and pathological examination of the lesion. This case highlights an uncommon etiology of Pancoast syndrome which might mislead physicians in their practice.