We describe a 7-year-old child who presented with a soft fluctuant swelling on the neck which became more prominent during the Valsalva manoeuvre. He underwent adeno-tonsillectomy based on a mistaken diagnosis of ballooning of the pharynx secondary to enlarged adenoids and tonsils obstructing the nasopharyngeal and oropharyngeal airways. Investigations revealed the swelling to be a markedly dilated internal jugular vein. We discuss the diagnostic features and mode of treatment of this condition so as to avoid unnecessary and dangerous surgical intervention.