An improved guide for a medical needle is disclosed herein. An aligning element for aligning a needle guide, which is equipped for longitudinally guiding a medical needle, includes a connecting element for arranging the aligning element on the needle guide, and a light-guiding element for a predetermined diffusion of light. The light-guiding element only generates a predetermined light pattern relative to the diffusion of light in a pose predetermined by the geometry of the apparatus. Such an aligning element may be used in a treatment arrangement for longitudinally guiding a needle and in a method for aligning a needle guide.
