In the early 1960's, lasers first appeared in the hands of biologists and medical researchers. They believed that this energy could be put to therapeutic use. A great deal of information regarding the absorption, transmission, and scattering of light by tissue has been compiled since that time. Today, lasers are used in many areas of medicine, including surgery, medical diagnostics, and biological assay. This communication will emphasize those medical applications in which laser energy is used to cut, ablate, cauterize, or selectively injure tissue.