This report summarizes the successful development project made by Stanley, in cooperation with Fisher Guide Division of CMC, in which a LED HMSL (Light Emitting Diode High Mounted Stop Lamp) outstripped the conventional incandescent bulb in performance, by utilizing super bright LED's as the light source.The major factor that made this project successful was Stanley's development of the world's brightest GaAlAs red LED, by using a manufacturing process of temperature difference, continuous liquid phase crystal growth technology which was realized based on the research of Dr. Junichi Nishizawa of Tohoku University. Up to this time, LED has only been used in the field of consumer electronics. However. Stanley accepted a request from GMC for the development of a LED HMSL and has studied all the optical, thermal, electrical structural and styling of LED's as an automotive light source. This has proven the feasibility of installing LED signal lamps onto automobiles.