We report the case of a 30-year-old man who experienced a potentially fatal haemorrhage on the tenth post-operative day after the development of a pseudoaneurysm of the muscular branch of the lingual artery. Due to the nature of the development of these pseudoaneurysms they are difficult to detect until such time that they present with a massive haemorrhage or a rapidly expanding parapharyngeal swelling. There are only several reported cases in the literature to date.