The idea for this book developed as an outcome of a multidisciplinary sym- posium entitled "Pituitary Adenoma Update" that was held at Tufts-New En- gland Medical Center in April 1977. The purpose of that symposium was to put together our current knowledge of the cause of pituitary tumors and discuss the diagnostic evaluation and management that was now appropriate, in light of the rapid advances that had taken place so recently in this area. Those of our colleagues who had presented papers at the symposium, as well as a number of others, were invited to contribute to this volume, which should serve as a presentation of the "state of the art" on all aspects of pitu- itary tumors. We felt that such a book would be of value to endocrinologists, neurosurgeons, neuroradiologists, and pathologists who are involved in the investigation or care of patients with pituitary disorders. For a number of reasons, a review of pituitary adenomas seems particu- larly timely. Rapid advances have taken place coincidentally in the fields of neurosurgery, neuroendocrinology, neuroradiology, neuropathology, and neuropharmacology. Seven major developments in these areas have occurred independently and almost simultaneously that have virtually revolutionized our approach to pituitary adenomas.