Background: The growing teratoma syndrome has been described with regard to gonadal and extragonadal germ cell neoplasms in males, but few cases have been reported in the female population. In this condition, masses that enlarge during or after chemotherapy are found to contain mature teratoma without malignant elements.Cases: Three patients had either persistent or growing masses despite chemotherapy for germ cell malignancies of the ovary. All cases fit the description of the growing teratoma syndrome. The patients were aged 20–22 years. All three patients had immature teratomas before chemotherapy. The stages of disease ranged from la to IIIc. All patients had normal tumor markers while their masses showed growth or persistence. All were free of disease 6–31 months after diagnosis.Conclusion: Growth or persistence of a tumor after chemotherapy for malignant teratoma does not necessarily imply progression of malignancy, especially if tumor markers are normal. However, these masses should be resected because they may cause obstruction, compression, or displacement of adjacent organs, or undergo sarcomatous degeneration.