The invention relates to a housing for a detection unit for optically detecting smoke particles. The detection unit has a light source for emitting radiation to be scattered by smoke particles to be detected and a light detector for detecting the scattered radiation. The housing 2 has a cylindrical outer surface 7 having smoke openings 8 through which the smoke particles enter housing 2, and a radially symmetric light-guiding structure 9 with guide members. The guide members are so designed that adjacent guide members each form a guide channel through which the radiation emitted from the light source and not scattered by the smoke particles is guidable to the outside in the direction of the smoke openings 8 by multiple reflection. Higher detection sensitivity for optically detecting smoke particles can be achieved as a result.