The NATO Advanced Study Institute "Biomedical Optical Instrumentation and Laser- Assisted Biotechnology" was held November 10-22, 1995 in Erice, Sicily. This was the 19 th conference organized by the International School of Quantum Electronics, under the auspices of the "Ettore Majorana" Center for Scientific Culture. The contributions presented at the Institute are written as extended, review-like papers to provide a broad and representative coverage of the fields of laser techniques, optoelectronics systems for medical diagnosis, and light and laser applications to Biology and Medicine. The aim of the Institute was to bring together some of the world's acknowledged scientists and clinicians that belong to different disciplines and consequently do not usually meet, but who have as a common link the use of optoelectronics instrumentation, techniques and procedures. Most of the lecturers attended all the lectures and devoted their spare hours to stimulating discussions. We would like to thank them all for their admirable contributions. The Institute also took advantage of a very active audience; most of the participants were active researchers in the field and contributed with discussions and seminars. Some of these seminars are also included in these Proceedings. The Institute was an important opportunity to discuss latest developments and emerging perspectives on the use of laser sources and optoelectronic techniques for diagnostic and therapeutic purposes.