The laser's range of application is extraordinary. Arthur Schawlow says, "What instrument can shuck a bucket of oysters, correct typing errors, fuse atoms, lay a straight line for a garden bed, repair detached retinas, and drill holes in dia monds?"O The laser's specifically biomedical uses cover a similarly broad and interesting spectrum. In this book, I have endeavored to convey some of the fas cination that the laser has long held for me. It is my hope that both clinicians and researchers in the various medical and surgical specialties will find the book a use ful introduction. Biologists, particularly molecular biologists, should also find a great deal of relevant information herein. This volume's distinguished contributors provide admirably lucid discussions of laser principles, instrumentation, and current practice in their respective special ties. Safety, design, capabilities, and costs of various lasers are also reviewed. We have aimed to create a practical text that is comprehensive but not exhaustive. Our emphasis on the practical, rather than the esoteric, is dictated not only by the short history of biomedical laser use, but by the extent of the community to which this information will appeal.