Solid-state erbium lasers operating at a wavelength of 2.9 microns are very new and have considerable potential as a surgical modality for procedures requiring precise cutting in biological tissue. The proposed effort would perform the scientific and engineering work needed to develop clinically useful laser hardware and energy delivery systems. In addition to hardware development, this program would develop specific surgical procedures that would demonstrate the anticipated efficacy of erbium lasers, by performing tissue, animal, and preliminary human studies. The ultimate objective is to develop several of these procedures to the point where multi- center clinical trials can begin.