This book has the ambitious aim of presenting the state of the art of the biology, clinical presentation and management of intra-cranial germ cell tumors. This rare group of tumors is fascinating for the scientist and challenging for the clinician. A precise pathological diagnosis and classification is necessary for an appropriate treatment. The tumors are located mainly in the pineal and supra-sellar regions and present with typical neuro-ophthalmological signs as well as endocrinological abnormalities. Sophisticated imaging techniques allow a precise anatomical definition, but only an approximate guess of the histology. Tumor markers are helpful to some extent when they are detectable. For this reason, surgery remains essential for the diagnosis. It is however becoming clear that in a certain subgroup, like germinomas, total resection is not helpful and stereotactic biopsy is enough because of the efficacy of radiotherapy. Recently, it has become evident that chemotherapy is also effective, allowing to reduce the dose of irradiation in order to avoid its complications. This is especially important since germ cells tumors are most frequently encountered in children and adolescents. With such aggressive treatment modalities, it is essential to carefully consider the side effects, both from the neurological and endocrinological points of view. Research into the origin, genetics and immunology of these tumors has brought fascinating information. All these aspects are considered in the various chapters of this book. Since a multi disciplinary approach to the management of these tumors is of utmost importance, we hope the book will be interesting to neurologists, oncologists, radiologists, neurosurgeons, as well as basic scientists. Indeed much remains to be improved in order to offer a satisfying treatment for the most malignant forms such as embryonal carcinomas, chorio-carcinomas and malignant teratomas.