Aim of the study: To assess the features identified on ultrasound in patients presenting with suspected extensor pollicis longus tendon rupture, and correlate this with surgical findings. Material and methods: A retrospective case series review was performed in 11 patients (8 female, 3 male) with suspected extensor pollicis longus tendon rupture. All ultrasound examinations were performed by an experienced musculoskeletal radiologist using a highresolution linear-array probe. The study evaluated the associated sonographic appearances of extensor pollicis longus tendon rupture and correlated with surgical findings. Results: Rupture of the extensor pollicis longus tendon was identified in all cases proximally at the level of Lister’s tubercle. The most common associated sonographic finding was an effusion in the sheath of compartment III (10 patients); 9 patients also had fluid within the sheath of compartment II. An empty tendon sheath was observed in 1 patient and tenosynovitis of the extensor pollicis longus sheath was demonstrated in 2 cases. In 9 patients, sonography revealed the retracted tendon ends as enlarged and hypoechoic with loss of their normal fibrillar appearance. Ultrasound depicted fracture involvement of Lister’s tubercle in 8 cases (compared to 4 cases identified radiographically). In the 8 cases that proceeded to operative intervention, all of these were confirmed as extensor pollicis longus tendon rupture. : Ultrasound is a valuable tool in identifying patients with extensor pollicis longus tendon rupture, providing the surgeon with invaluable details with regard to the level of rupture to aid pre-operative planning. US identifies associated ancillary features of extensor pollicis longus tendon rupture and reliably detects fractures involving Lister’s tubercle.