The ionization of free atoms in flames is a well-known effect and its relevance in atomic absorption spectroscopy is discussed in standard texts(1), (2)For analytical purposes it is important to know whether the degree of ionization will be significant for a given element under selected operating conditions. Appropriate compensation for the effect can then be made if necessary. This note presents tabulated values for the percentage ionization of almost all elements determined by atomic absorption spectroscopy for the three flames most commonly used in this technique. These values were calculated by an ICI. 4130 computer, using a program written in Fortran IV, from the Saha equation(3).