Chapter 18 covers the basic science and clinical topics relating to respiratory medicine which trainees are required to learn as part of their basic training and demonstrate in the MRCP. The chapter starts with an introduction to the respiratory system, before covering respiratory defence and physiology, respiratory investigations, respiratory failure, pneumonia, tuberculosis, cystic fibrosis, bronchiectasis, pleural effusion, chronic obstructive pulmonary Disease, adult respiratory distress syndrome, asthma , fungal lung diseases, pulmonary embolism , lung cancer, pulmonary fibrosis, extrinsic allergic alveolitis, occupational lung diseases, sarcoidosis, Cor pulmonale and pulmonary hypertension, pneumothorax, cough and haemoptysis, pulmonary eosinophilia, and obstructive sleep apnoea.