The topics chosen for discussion represent the most common problems referred by family doctors to chest clinics. It was taken for granted that the reader will be familiar with the symptoms, signs, and natural history of respiratory diseases, so that the stress is on differential diagnosis and treatment. Tuberculosis once occupied nearly all the time of chest physicians. At present weeks go by without a single case presenting itself. There has been no comparable improvement in cancer of the lung, which remains one of the most intract able problems. Asthma was seldom referred to out-patient clinics when the disease was regarded as more unpleasant than dangerous. The hazards of severe attacks and the advan tages of liaison with a hospital department are now widely recognized. A similar change of attitude to the management of chronic bronchitis brought many new patients to the chest clinics in place of the vanishing tuberculous population. Some uncommon pulmonary diseases are included: allergic alveolitis, because of the importance of early diagnosis, and sarcoidosis in order to discourage unnecessary treatment. The book is intended to be a practical guide and is not a critical review. This might serve as an excuse for its didactic style and the exclusion of controversial subjects. Some statements are repeated at more than one place in order to help readers who wish to consult individual chapters bearing on some current problem. Source references are omitted and are replaced by a short list of books recommended for further reading.