The invention relates to a light mixing assembly for a medical or dental illumination device in particular for a light hardening device for polymerising dental masses. Said device comprises a housing having a light generating device in addition to an optical wave guide. Said light mixing assembly (2) comprises a rod shaped light mixing body (8) preferably with at least one transparent material in particular glass and a holding device (7) which enables the light mixing device (2) to be mounted between the light generating device (1) and the optical wave guide (3) and is held in position in a detachable manner from the optical wave guide.
