The use of synthetic amino acids (AA) in diets for pigs has increased in the past few decades due to increased availability and reduced prices of these AA. The increased use of synthetic AA has caused a reduced need for inclusion of soybean meal (SBM) in diets. For instance, a common grower pig diet without synthetic AA needs around 35% SBM to full fill the requirements for all indispensable AA, but a diet with 5 synthetic AA only requires 17% SBM. It has generally been assumed that pigs fed diets containing synthetic AA will have growth performance, protein deposition, and carcass quality that is no different from that of pigs fed diets based in which the majority of the AA are furnished by SBM as long as the requirements for all digestible AA are met. It has also been assumed that diets formulated with large amounts of synthetic AA, compared with diets based on SBM provide more net energy to pigs because these diets contain more corn and less SBM. However, some of these assumptions are not based on strong scientific evidence, and results of recent research has raised doubts about previously assumed effects of using synthetic AA. Therefore, the objective of this experiment was to test the hypothesis that the use of synthetic AA instead of some of the intact protein from SBM does not impact growth performance, carcass composition, energy deposition, blood cytokines or abundance of intestinal amino acid transporters when fed to growing pigs.