This outstanding issue of the "Endocrinology and Metabolism Clinics of North America" explodes the myth that pituitary diseases are rare. New studies have found a significantly increased incidence of pituitary tumors. Similarly, the incidence of hypopituitarism goes up steadily with the rising numbers of long-term survivors of cancer, massive head trauma or subarachnoid hemorrhage. Recent years have witnessed major refinements in our ability to visualize pituitary lesions using MRI studies. Similarly, there have been major therapeutic advances: minimally-invasive transnasal surgery, computer-driven radiation techniques and several new medications. The changed landscape of pituitary endocrinology was the impetus behind assembling the leading experts in the field to summarize the contemporary state-of-the-art knowledge in this fascinating area. This monograph was designed not so much for the narrowly-defined pituitary specialists, but mainly for general clinical endocrinologists, endocrine fellows and medical students and residents.