Congenital cystic adenomatoid malformation (CCAM) of the lung is a neonatal disease not often found after the first year of life and extremely rare in adults. Three cases of CCAM, one in a ten-year-old girl and two in adults, are reported. An understanding of this disease is important because, although relatively rare, it is one of the most frequent causes of neonatal respiratory distress. Greater awareness of the condition and its early detection would also reduce the number of cases found at a later age.