The so-called percutaneous dilatational tracheostomy-essentially a minimally invasive puncture method-inserting the tracheal cannula by a modified Seldinger-technique is an alternative method to the conventional operative tracheostomy. The percutaneous dilatational tracheostomy was evaluated in a prospective trial (June 92-January 93) on 50 consecutive surgical (n = 36), medical (n = 10), and neurological-neurosurgical (n = 4) critically ill patients (29 m, 21 f; age 14-87 years) with need for prolonged mechanical ventilation. After an average duration of endotracheal intubation of 6 (0-22) days, the procedure was endoscopically guided and controlled via the endotracheal tube. An 8 mm cannula was inserted in each case. Eight patients had severe thrombocytopenia (< or = 50,000 Plt./microL). The percutaneous tracheostomy was always performed with success. The average procedure duration was 8 (5-15) minutes. The perioperative complications were: one patient died of acute cardiac failure independent from the method of tracheostomy, one sustained a temporary subcutaneous emphysema and one a minor bleeding. During a mean duration of cannulation of 21 (0-113) days only one bleeding from the skin margin was observed postoperatively. Infection of stoma site, misplacement of cannula, rupture of the tube cuff, and pneumothorax were not noticed. On 13 decannulated patients stenosis of the trachea was not found in a period of 6-8 weeks following the tracheostomy. As a bedside procedure the percutaneous dilatational tracheostomy is safe and quick and should therefore be the method of choice for critically ill patients who require a tracheostomy.