We used portable ultrasound scans to identify relevant anatomical structures in the necks of 30 patients before percutaneous tracheostomy. We identified the tracheal midline, thyroid isthmus and blood vessels and located a safe level for needle insertion. Anterior jugular veins were seen in 15 patients; eight were near the midline and were considered vulnerable. Three veins were more than 4 mm in diameter and these larger vessels were electively ligated. Four patients had arteries which were considered vulnerable to damage. All patients underwent successful percutaneous tracheostomy. Portable ultrasound provides a simple method of screening for vulnerable blood vessels in the neck and for locating the midline before percutaneous tracheostomy. This method is particularly suitable for patients with landmarks that are difficult to visualise or palpate. Based on the ultrasonic findings we can make an informed decision about referral for surgical tracheostomy.