BACKGROUND Hydatid disease is common in Libya with a prevalence of 2%. Surgery of pulmonary hydatid disease remains the best treatment and aims to remove the cyst or its remnants and obliterate the residual cavity. METHODS Forty three consecutive patients under 15 years of age were investigated by plain chest radiography, ultrasonography of the abdomen, and indirect haemagglutination tests. At thoracotomy the parasite or its remnants were removed and the bronchial fistula sutured. RESULTS All but four of the patients were discharged within 12 days. These four had had their large cavities obliterated by purse string sutures and developed air fluid levels with cavity reformation at the cyst site. They were treated conservatively by physiotherapy and antibiotics and remained in hospital for 2-3 weeks. There was only one recurrence after three years of follow up. CONCLUSIONS Pulmonary hydatid cysts in children can be treated successfully by evacuation and obliteration. The methods described can also be applied to adults.