The relief of pain by laser therapy in useful in the treatment of ulcers burn, tenosynovitis, tendinitis, bursitis, neuritis, rheumatism, chilblains, herpes, zoster. The degenerative cells probiferate to replace by the active vigorous cells by laser rays and suppressed the growth of cell in pathological lesion or condition laser rays promote healing by stimulating growth of celt or tissue The purpose of this study was to introduce about the principles of therapeutic laser ray, characteristics, indication, contraindication, technique, therapeutic effect or clinical effect throughout refference books. The author believe that therapeutic laser rays will contribute grently toward over coming the difficulties of physical therapy.