Mechanical ventilation is an important part of intensive care. It requires intense observation and has several severe complications. Weaning from mechanical ventilation should be started as soon as possible and immediately after the cause of the pulmonary dysfunction has been treated. Weaning is a continuous process with the aim of shortening the period of mechanical ventilation, and the progress can be managed by personnel-driven or automatic protocols. In this article we describe factors that predict a successful endotracheal extubation.