Hydatid disease still remains an important public health problem in many temperate and subtropical areas of the world. Hydatid disease is very rare in Korea. Recently, increase of abroad employment and tour into the endemic area brings into increase of the disease. We experienced a surgical case of unilocular hydatid cyst of lung in a 26 year old man. He had worked for a year[1986] in Libya. Hydatid cyst in left lower lobe was treated by lobectomy.