Hydatid cysts represent a true social problem in Tunisia where 2.1% of rural inhabitants are affected. Hydatid disease is responsible for 10% of the country's surgical activity and costs approximately 800 $ per patient. From April 1967 through January 1987, 1,195 cases of hydatid cyst in children aged 2 to 15 years were treated at the Children's Hospital in Tunis. The involved organ was the lung in 643 cases, the liver in 486 cases, the spleen in 27 cases, and the kidney in 18 cases. With the exception of seven patients with malignant forms, surgery was always performed, with a 1.4% mortality rate and a 2% morbidity rate. We analyze the diagnostic and therapeutic particularities of the various locations of hydatid cyst. Diagnosis rests mainly on ultrasound findings and treatment on conservative procedures as hydatid disease in children carries a good prognosis.