Three bite registration waxes were tested for their thermic dimensional behavior under several heating and cooling conditions. Aluwax showed the smallest changes in length. Difficulties of application are expected because of its low softening temperature. There were greater dimensional changes with Beauty Pink Hard-Wax, but Kerr No. 8-Wax showed the greatest changes. The cooling method had a small, the heating temperature, however, a strong influence on the thermic dimensional behavior. These are the recommendations for the clinical application of the tested waxes: The bite registration material should not be heated more than necessary for achieving a sufficiently plastic quality for the registration. It should be stored in ice water to be resistant enough to deformation during the model mounting.