We present a case of septicaemia caused by Arcanobacterium haemolyticum in a previously healthy 23-year-old man suffering from acute pharyngotonsillitis, who developed complicated Lemierre's syndrome. Three blood cultures (both aerobic and anaerobic) revealed the exclusive presence of A. haemolyticum. The presence of Fusobacterium necroforum was not essential for the development of this pathology. To our knowledge, this is the first reported case of Lemierre's syndrome caused solely by A. haemolyticum. We confirm that this organism must be considered a potential pathogen in immunocompetent patients.