Ventilatory dysfunction is often caused by disease, surgery, anaesthetic drugs and techniques, but preservation of adequate gas exchange and lung function is most vital for safe anaesthetic management and outcome of the procedures. These patients need proper preoperative evaluation (medical history, physical examination, laboratory studies, etc.) and preparation before anaesthesia. Skillful conduct of anaesthesia and intraoperative monitoring are important. This chapter discusses some common respiratory diseases like chronic obstructive pulmonary disease (COPD), bronchial asthma, pneumothorax, aspiration pneumonitis, pleural effusion, empyema, pulmonary embolism, adult respiratory distress syndrome, etc.