"Modem Neurosurgery of Meningiomas and Pituitary Adenomas" presents the state-of-the-art of neurosurgery for these two types of tumors. Following a classification of the pituitary adenomas according to pathology, molecular biological factors are presented and their effects evaluated as these aspects deepen our understanding of the growth and further expansion of these tumors. The diagnosis is made not only by a study of the hormonal status, but also by neuroradiology. A number of authors have devoted their efforts to the special problem groups such as the elderly patients and those with huge pituitary adenomas. Particular emphasis is of course placed on the surgical treatment, including transcranial and transphenoidal neurosurgery, but the use of medical treatment and irradiation must be discussed as well. The treatment of meningiomas has also been influenced by the molecular biology of hormone and growth factors. Therefore it is accorded extensive space in this volume. The prognostic significance of nuclear DNA content is discussed. Recent research with new diagnostic methods such as somatostatin scintigraphy, PET studies end progesterone receptor in tumor fragment spheroids is presented here. The treatment of these tumors, however, depends largely on their localization. For the neurosurgeon, the surgical treatment of meningiomas involving the cavernous sinus, meningiomas of the ventral Foramen of Monroe, meningiomas of the cerebello­ pontine angle and of the optic sheath is presented by prominent experienced leaders in this field.