Currently, tracheostomy represents an established procedure for airway management in critically ill patients who require long-term respiratory support, and it is one of the most frequently performed surgical procedures in critically ill patients. It offers a number of practical and theoretical advantages when compared to conventional translaryngeal oro- or nasotracheal intubation, but is also associated with a number of serious complications. In the last 20 years, several retrospective studies, randomized prospective trials, and meta-analyses have been published to determine the best timing for tracheostomy. However, these studies presented conflicting results. All studies performed so far in a prospective randomized fashion were relatively small and underpowered. Currently, several large controlled randomized studies are underway that will hopefully help physicians make better evidence-based decisions on the timing of tracheostomy. Based on our current knowledge, the following recommendations might be made on a low level of evidence: on day 2 or 3 after onset of mechanical ventilation (>48 h of mechanical ventilation or need for an artificial airway) tracheostomy should be seriously considered. Before decisions are made, several questions should be answered: Is the situation suitable for tracheostomy? Are there relevant contraindications for the performance of a tracheostomy? What is the most likely course of the underlying respiratory insufficiency? What is the likelihood the patient will stay in need of invasive mechanical ventilation for more than a week, either because of an ongoing impairment of oxygenation, weaning failure, upper airway obstruction, coma or a swallowing disorder? If no relevant contraindication is present and if the need for invasive mechanical ventilation can be expected to last for more than one week, tracheostomy should be planned and performed within the next 2 days.