Germinoma represents 7.8% of cerebral tumors in pediatric age and 50-65% of germ cell cerebral tumors. Generally it is a definite lesion of the pineal gland or suprasellar region, frequently occurring in the first three decades of life. Clinical presentation depends on tumor localization. Pineal lesions generally determine symptoms due to the compression of cerebral structures, causing Parinaud syndrome, while hypothalamic lesions are often characterized by diabetes insipidus, hypopituitarism and visual defects. In the absence of these classic signs and symptoms, however, the diagnosis of germinoma can be difficult. We presented the case of an 8-year-old boy, referred to our clinic for polyuria and polydipsia. Hormonal evaluations demonstrated central diabetes insipidus (CDI), with normal anterior pituitary function. Magnetic resonance imaging (MRI) showed a lack of posterior pituitary gland and partial pituitary stalk enlargement. The patient started therapy with desmopressin (Minirin) with good hydro-electrolytic balance. During follow-up the pituitary function became insufficient with low growth velocity. A second MRI demonstrated a bifocal lesion with dyshomogeneous and cystic appearance, suggesting the diagnosis of germinoma. On the basis of this case report we would like to point out the importance of an early diagnosis in order to improve the prognosis of the disease and the necessity of a careful follow-up of these patients.