The authors present a retrospective study of 12 cases of cystic adenomatoid lung malformations in clinical surgery unit "A" at the Rabat Children's hospital, between 1999 to 2006. Two pregnancies with lung malformation were identified. All of the patients were symptomatic. The treatment was surgical in all cases (lobectomy: 11 cases; pneumonectomy: one case). The evolution was good after an average of three years. In the light of these 12 malformations, the authors try and demonstrate the value of early diagnosis in order to surgically treat the anomaly in optimum conditions. Moreover, the authors insist on the exeresis not only of the malformation, but of the entire lobe involved in anomaly to guarantee a recurrence-free result.