Growing teratoma syndrome is an uncommon complication of malignant germ cell cancer, characterised by the development of large tumours during or after chemotherapy, despite normalisation of tumour marker levels and metastasis, which contain only mature teratoma. Given its low incidence, little is data available. The authors present the case of a 15-year-old girl with a growing teratoma and the literature review outlines the current knowledge of its pathogenesis, common sites, diagnosis, natural course, treatment, and prognosis.