The goal of the present study was to objectify whether the design modes of "Correlation", "Function", and "Extrapolation" of the Cerec 2 system are suitable for generating a functionally perfect occlusal surface of a first mandibular molar crown. For this purpose, an occlusal surface was waxed up according to the biomechanical concept of MH Polz, and this served as the reference occlusal surface. Four different Cerec 2 comparison crowns (produced in the laboratory, Extrapolation mode, Correlation mode, Function mode) were produced and the positions of the cusps were measured. It was shown that the Correlation mode delivers the most accurate results, and the manually produced occlusal surface also showed good results. The occlusal surfaces of the crowns produced according to the Extrapolation and Function mode were clearly inferior. Keywords: all-ceramic crown, Cerec, occlusal surface