Abstract: This paper gives the 2006 self-consistent set of values of the fundamental physical constants and conversion factors recommended by the Committee on Data for Science and Technology (CODATA) for international use. This set replaces the previously recommended 2002 CODATA set. Although only four years have elapsed between the 31 December 2002 and 31 December 2006 closing dates of the two adjustments, a number of advances in experiment and theory have led to significant improvements in our knowledge of the values of the constants.