Abstract
The diagnosis of Hydatid of the Lung cannot be made definitely on X-ray appearances alone, although in countries where this disease is common, the probabilities are that the tumour seen is an hydatid. The change of contour noticed on deep inspiration will be in favour of an hydatid cyst. The X-ray appearances must be considered along with blood counts, especially for an eosinophilia, and immunological reactions. In the case of the ruptured cyst, the X-ray appearances are indefinite, but fortunately the immunological reactions are very definite. Sputum examination will often reveal the presence of hooklets or hydatid membrane. These findings clinch the diagnosis.