Patients with intracranial germ cell tumor (IGCT) often present with pituitary dysfunction, including diabetes insipidus (DI). Recent protocols have used pre-radiation chemotherapy with combinations of etoposide, carboplatin and/or cisplatin, and ifosfamide. Management of DI in these patients requires monitoring of electrolytes and fluids during chemotherapy and hyperhydration. All consecutive patients treated with chemotherapy for an IGCT during the period 1990-2007 at the Hospital for Sick Children, Toronto were reviewed. Out of 32 patients who received chemotherapy, 21 had DI. Only cycles containing cisplatin and/or ifosfamide and hyperhydration were considered. DI and non-DI patients were compared for each cycle of chemotherapy. Patients were studied for number of days in hospital per chemotherapy course, daily fluid input and output, changes in dose, schedule and route of administration of desmopressin (DDAVP) during chemotherapy, daily variations in sodium level, electrolyte monitoring requirements per day, and complications related to fluid and electrolyte disturbances. Fifty-four cycles of chemotherapy in DI patients were compared to 25 cycles in non DI patients. All 21 patients with DI required daily change in dosage and schedule of DDAVP. Marked variations in daily sodium level were observed in the DI group. Seventeen courses required prolonged admission in the DI group (one in non DI patients) and 6 patients experienced serious complications. In conclusion, DI is a risk factor for complications when cisplatin and/or ifosfamide based protocols are used. The role of these agents in the management of ICGT should be carefully evaluated and guidelines for management of DI established.