Fontan procedure is a palliative surgery done for patients born with single ventricle physiology. An understanding of the hemodynamic alterations in such a patient is important for successful perioperative management. We have discussed the anaesthetic considerations in a 12 year-old girl with complex congenital heart disease ultimately palliated by a Fontan operation, who was posted for Botox injections for upper limb spasticity under general anaesthesia.