Results of clinical examination and laboratory investigations of overt and suspected cases of hydatid disease in Egypt revealed that the disease is more prevalent among young persons directly associated with dogs,urban rather than rural and affects more frequently the liver than the lungs. The I.H.A.T never failed in diagnosis of the disease while the C.F.T much lower titres.Eosinophilia was not a permanent feature while casoni test was not always positive indicating its low grade sensitivity and specificity