Abstract: An LED lamp allows the emitted LED light to be directed substantially in a desired direction. The LED lamp comprises an LED and a transparent housing for accommodating the LED. The transparent housing has a substantially semi-convex top formed with at least a total reflection plane. When the LED is placed at a specific position, part of the emitted LED light that strikes on the total reflection plane will be totally reflected from the total reflection plane. As a result, if the LED lamp is placed horizontally, as for example when mounted on an upright installed commercial sign, the emitted LED light rays will be virtually all directed at descending angles that allow people passing by the commercial sign to see the sign more clearly.