together with the oncologist. For man, the laser must be moved out of the laboratory into the operating room. At present, its true position in the cancer therapy program is not yet known. The greatest attention is being directed to melanoma because of the tremendous energy adsorption capabilities of this heavily pigmented tumor. The next area of interest is in uncommon and com- mon tumors of blood vessels. Here, too, the color factor influences to a signifi- cant degree the absorption of the laser. Multiple accessible malignancies are treated also by the laser chiefly to compare the effect here with other modalities of therapy. Finally, as a type of therapy of desperation, lasers are used in the treatment of metastatic lesions. This then, is the brief introduction to the study of the current status of laser cancer research. Intense, difficult and cooperative research of the next few years will determine the role of the laser, an optical knife , as an investi- gative or therapeutic instrument. T able of Contents Chapter 1 Laser Instrumentation 1 Chapter 2 Laser Protection . 8 Chapter 3 The Laser Reaction in Tissue 13 Chapter 4 Color Qualities of Tissue in Relation to Laser Radiation 16 Chapter 5 Laser Radiation of Tissue Cultures .