Abstract: An apparatus is disclosed for sterilizing dental hand pieces 80. The apparatus comprises a treating chamber 22. Different channels 41-44 in bottom plate 36 of the chamber 42 connect the interior of the chamber and the hand piece 80 with saucers 62-68 of water pressurized air, oil and steam. The connection is effected through conduits arranged as channels in a metal block 50 and through valves arranged in a valve block 60. Accordingly, maintenance and mounting is easy. Moreover, safety switches 96 for the movement of the lid 4 of the chamber 22 are provided in a foil 90 arranged around the holding of the treatment chamber, which switches 96 are pressure sensitive membrane switches operating with elements 100 on the lid 4.