The cause of the Williams Campbell syndrome (bronchomalacia with bronchiectasis) is controversial. A boy with bronchomalacia, bifid ribs, and left bronchial isomerism presented with intractable wheeze mimicking asthma. The combination of the abdominal, bronchial, and atrial anatomy seen in this child has been described only once previously. The coexistence of these congenital abnormalities in this boy supports a congenital cause for the Williams Campbell syndrome. The need to assess wheezy children critically is emphasised.