Antenatally diagnosed lung lesions are most commonly congenital cystic adenomatiod malformations (CCAMs) or bronchopulmonary sequestrations (BPS). Congenital lobar emphysema and bronchogenic cysts occur rarely. CCAMs and BPS can only be truly distinguished on histopathological assessment. CCAMs can be defined using either Stocker's histological classification, or the clinically more useful 'macrocystic' and 'microcystic' subtypes introduced by Adzick. Adverse pathophysiological effects (e.g. lung hypoplasia, mediastinal shift, caval obstruction and hydrops) can occur with those of larger volume in the developing fetus and are associated with a poor outcome ( approximately 5%). In centres with appropriate expertise, antenatal intervention (e.g. thoracoamniotic shunting) should be considered for such cases. In the postnatal period, early radiological evaluation (e.g. CT scan) is essential as many cases which apparently 'regress' antenatally are still detectable and may be a cause of later morbidity. Early surgical excision is required for symptomatic cases and should also be considered for asymptomatic antenatally diagnosed lesions, because of the risks of later infection and the possibility of malignant transformation. An excellent outcome following surgery can be expected.