This has become the standard reference text on respiratory diseases in children. The fourth edition has been extensively revised and updated to encompass the latest developments. There are now specific chapters on obstructive sleep apnoea and the lung in HIV infection. The most change in existing chapters comes in those on growth and development, respiratory noises, cough and pulmonary consequences of inhalation. The clinical approach in this book is strongly based on an understanding of epidemiology, pathophysiology and increasingly, molecular biology and this fourth edtition brings a stronger theoretical basis to the clinical practice that has been one of the strengths of previous edtitions.