Contrary to conventional light sources in headlamps, LEDs do not produce heat radiation to the fore. The heat resulting from the operation of the LEDs occurs at the LED submount and is transferred by conduction into a cooling element that is - due to its function - mounted in the back of the LED(s) and therefore in the back of the headlamp. This contribution describes the development of an active headlamp cooling system and is focusing on special aspects regarding LED-headlamps. Thermal aspects are shown in various simulations and have been approved in road trials and laboratory tests. An active cooling system - based on the counter flow principle - is a very adequate way to cool down the light sources in a LED headlamp. Thereby it is irrelevant whether a projection system using lenses or reflection system using reflectors is considered. The heat from the LEDs is transferred from the back of the headlamp, where it arises, to the most efficient cooling zone - the outer lens. So it is guaranteed that cooling is as efficient as possible. Furthermore it is a very good way to avoid fogging or icing of the outer lens, because there is a warm air flow toward the important zones all the time. The dispersion of the warmth is more homogeneous than in state-of-the-art headlamps with incandescent or HID-systems producing hot spots due to heat radiation. The LEDs drive current has a high influence on the system temperature. In case that LEDs become more efficient in terms of their light output, the drive current can be limited to a lower level. This leads to a cooler system with a consequence that peak temperatures, which may damage the LEDs in critical thermal situations, do not occur any longer. There will be no longer the need reducing the LED's power for decreasing the heat build-up and the full light performance will become available all the time, also under extreme conditions like 'a traffic jam in a dessert'. Then the de-fogging and de-icing will remain the mean function of an active cooling system.