The differences between a contact and non-contact Er:YAG laser hard dental tissue preparation were verified. The influence of laser energy and number of pulses on a profile and depth of a drilled cavity was investigated. The delivery systems used were an articulated arm and a cyclic olefin polymer-coated silver hollow glass waveguide with or without a special sapphire tip. In the case of the non-contact preparation, the laser radiation was directed onto the dental tissue by focusing optics (CaF2 lens) together with the cooling water spray in order to ensure that the tissues will not be burned. The water spray was also used during the preparation when the waveguide with a sapphire tip was used to deliver the radiation. For the evaluation of shapes, depth and profiles of the prepared cavities the metallographic microscope, photographs from the light microscope and scanning electron microsec were used. From the result it follows that great differences exist in the laser speed, value of energy, the profile, and depth of the cavities prepared by the contact and non-contact preparation. In the case of contact ablation the procedure is quicker, the energy fluence needed is lower and more precise cavities with larger diameters are produced.