The authors describe a case of a giant intracranial mature cystic teratoma in a 16-year-old girl presenting acutely with a severe headache, vomiting and a complex generalised seizure with a background history of intermittent headaches for 3 years. CT and MRI brain demonstrated a ruptured large cystic teratoma encapsulating two large teeth within the diffusely dense fatty heterogeneous lesion. Surgical debulking of the cyst was performed and the calcific remnants were left behind owing to dense adhesion to the brain. The procedure was complicated by postoperative hydrocephalus and needed a ventricloperitoneal shunt. She is currently asymptomatic and undergoing rehabilitation.