Bronchoalveolar lavage has a well established role in the diagnosis of pulmonary infections, particularly those due to opportunistic organisms in an immunocompromised host. Recent studies of infants and adults with inflammatory lung disease have helped our understanding of the mechanisms underlying these disorders and their responses to treatment. With increasing recognition that pulmonary events in utero and in early infancy are important in the pathogenesis of lung diseases such as asthma, studies of the lung's responses to various environmental insults in this population might guide us to developing effective preventative and therapeutic strategies. Bronchoalveolar lavage is one method for assessing a number of pulmonary components and may be useful in this regard, particularly if combined with new methods for examining inflammatory responses, such as those utilising the polymerase chain reaction to assess cellular expression for inflammatory cytokines and growth factors.