We present the case of a 25-year-old man who developed a brachial artery pseudoaneurysm and a subsequent haematoma after a penetrating injury with a window glass. A surgical excision of the pseudoaneurysm (anterior access) and a drainage of the haematoma were performed. After surgery, the patient developed a median nerve paresis, secondary to the postsurgical scar located in the elbow flexure. The diagnosis of these two entities was performed with ultrasound. Ultrasonography is an excellent imaging tool to make the diagnosis of pseudoaneurysms and nerve pathology, determining the presence, localization and extent of neural damage.