An illumination device is provided with an LED (2) as a light source and with a fiber-optic (6) for leading further the light which is emitted by the LED (2). A light transmission part (10) is arranged between the LED (2) and the fiber-optic (6). This light transmission part (10) includes two sections (14, 16), of which a first section (14) directly faces the LED (2) and includes a cross section which widens with an increasing distance to the LED (2) as well includes a lateral surface (22) which in an angularly independent manner reflects the radiation which enters into the first section (14) and a second section (16) directly faces the fiber optic (6) and includes at least one lateral surface (24) which in an angularly dependent manner reflects radiation which enters from the first section (14) into the second section (16).