An illumination system has a plurality (2) of light-collimating sections (12, 12', 12'') and a light-mixing section (3). The light-collimating sections are arranged substantially parallel to each other along a longitudinal axis (25) of the illumination system. Each of the light-collimating sections is associated with at least one light emitter (R, G, B). Each of the light emitters is being in optical contact with the respective light-collimating section via a dielectric material with a refractive index larger than or equal to 1.3. At a side facing away from the light emitters, the light-collimating sections merge into the light-mixing, the light-collimating sections and the light-mixing section forming one integral part. Light propagation in the light-mixing section is based on total internal reflection and the light-mixing section has a plurality of faces parallel to the longitudinal axis. Preferably, the light-mixing section at a side facing away from the light emitters is provided with a further light-collimating section.