The practical use of the Function program mode in Cerec 3D is demonstrated in the present patient case. The author performed almost all restorations with the previous Cerec 3 software using the Correlation mode. This has not changed with the new 3D program. Correlation is now used almost always jointly with Function. Whereas the Function mode in Cerec 3 was still an independent option, Function is now selected automatically by the program when optical impressions of the antagonist are taken. Keywords: Cerec 3D, correlation, function, registration, antagonist