This study evaluated the clinical and radiological characteristics, as well as the treatment outcomes, for the rare phenomenon known as intracranial growing teratoma syndrome (iGTS). One hundred seventy patients diagnosed with intracranial germ cell tumours (GCT) between 1997 and 2008 were enrolled in this retrospective analysis. Thorough reviews of medical records, brain magnetic resonance images (MRI), pathological findings and tumour markers [alpha-fetoprotein (αFP) and beta-human chorionic gonadotropin (βHCG)] were performed to identify the incidence of iGTS cases and to clarify their clinical characteristics. Eleven out of the 170 intracranial GCT patients (6.5%) were identified as having iGTS. All instances of iGTS originated from non-germinomatous GCT (NGGCT), with incidence rate of 21% (11/52). Six iGTS cases developed from mixed GCTs, four from immature teratomas (ITs) and one from yolk sac tumour. All 11 iGTS patients showed honeycomb-shaped multi-cystic growth patterns on MRI, which is a typical characteristic of iGTS. Surgical excision was performed in all patients, and complete excision was possible in nine patients. Eight of them are alive with no evidence of recurrence; however, two patients who had residual masses died owing to progression of iGTS. Early recognition and suspicion of iGTS, during or after adjuvant therapy of NGGCT, is crucial to ensure that surgical intervention can be performed in a timely manner. Early radical excision may be the treatment of choice for better iGTS prognosis.