A cross sectional study compared the clinical features of the pulmonary and hepatic hydatid cysts in children and adults and evaluated IHAT and ELISA techniques in diagnosis. The results showed that the patients ages were 5-14 years (10.6±3.7) in children and 16-75 years (32.2±14) in adults, patients 34 (75.5%) had liver cysts, 25 (55.5%) had pulmonary cysts and 7 (15.5%) had both liver and lung cysts. In hepatic hydatidosis, 7/34 (20.5%) cases were asymptomatic while others showed variable clinical manifestations. The commonest symptom was localized right hypochondrial pain in 13 (38.2%) and the least one was jaundice in 4 (11.7%). The commonest sign was abdominal masses on the right hypochondrium in 88.2% and the least one was ascites in 5.8%.The commonest symptom of pulmonary hydatidosis was chest pain in 8 (34.7%) followed by cough and hemoptysis on 4 (17.3%) and the least one was cough and fever (8.6%). Pulmonary hydatid cysts in children were significantly higher in males (17.3%) than females
(4.3%), but without significance in adults (26% in male vs. 21.7% in females). Sex difference in hydatid cyst frequencies between adults and children was significant (P <0.05). Mixed hepatic and pulmonary cysts were less in children than in adults (14.3%vs 85.7%), with huge pulmonary cysts of 20 cm were more common in children (37.7%) than in adults (17.7%). The high sensitivity (95.5%) of ELISA-IgG recommended this test showed a dependable sero-diagnosing one.