Intermittent postive pressure ventilation (IPPV) was invented at least 200 years ago, but it was not until the 1950s that prolonged IPPV was used to treat poliomyelitis1 , the acute respiratory failure of chronic lung disease2, and tetanus3. The commonest use of IPPV remains during anaesthesia, but the treatment is also applied to very varied diseases in the general intensive care unit (ICU). IPPV is now considered whenever the respiratory status of the patient is in jeopardy, is likely to become so, or when respiratory failure effects other body systems. This chapter reviews the general principles and new developments. The author trained in both general medicine and anaesthesia. He spent several years researching in intensive care and is now establishing a multi-disciplinary unit.