The purpose of this study was to evaluate the distortion of 6-unit etched bridge during the firing cycle. Thirty frameworks were constructed. Twenty of the frameworks received a normal application of porcelain and firing sequence ; ten served as controls and subjected to the same firing sequence without the porcelain application. The results were as follows ; 1. Distortion did occur in the body of curved, long-span etched bridge frameworks during the porcelain firing cycle. 2. This distortion was a result of changes in the metal as well as the contraction of fired porcelain. 3. The greatest distortional changes occurred during the degassing stage and final glaze stage of the porcelain firing cycle. 4. Distortion incurred by the application and firing of the porcelain was reversible. When the porcelain was chemically removed from the frameworks, there was an elastic rebound. 5. Distortion was clinically important.