Abstract: A light guide, particularly for medical instruments with a light guide fiber, which is surrounded, if needed, by a protective jacket, a sleeve which surrounds the light guide fiber at a distance therefrom and consists of one or several tubes and a feeding unit on one side of the light guide for the feeding of light radiation into the light guide fiber. The light guide fiber and a tube of the sleeve are mounted in the feeding unit, while the other end of the light guide fiber is mounted in the tube of the sleeve. A length compensating element that can change its length axially but is largely not expandable radially, is set in the sleeve to prevent stresses acting longitudinally on the sleeve and light guide fiber due to bending, especially during the coiling of the light guide fiber.