The recent revolution in medical imaging has demanded concurrent development of sophisticated and compatible stereotactic guiding devices in order to diagnose or treat mass lesions on the brain and disorders of cerebral physiology. Between July 1, 1979, and July 1, 1989, 1,006 patients underwent image-guided stereotactic surgery at the University of Pittsburgh. During this 10-year interval the first dedicated computed tomography stereotactic operating room and the first North American radiosurgical suite containing a 201 60Co source gamma knife were constructed. Early in our experience, 60.5% of the patients underwent diagnostic (biopsy) stereotactic surgery whereas, by 1988, 77.8% of the patients underwent therapeutic stereotactic surgery. At our institution, stereotactic surgery was performed last year in 257 patients, representing 19.9% of all neurosurgical operations. During the past 10 years, stereotactic surgery has developed an integral and definitive role in contemporary mainstream neurosurgery. Across the world stereotactic technology is now widely available. In the future increasing emphasis will be placed on therapy, image integration, computer software development, and new instrumentation designed to meet the evolving needs of neurological surgeons who demand safe, precise, and effective tools to explore the brain.