The report considers the stress fatigue limit CrD, the fatigue to ~ensile strength ratio oD/R m, and the deformation fatigue limit SD of pure metals. For FCC and some HCP metals there exists a linear correlation between fatigue limit and tensile strength. The fatigue limit and the fatigue ratio CrD/R m depend upon the homologous temperature. The fatigue ratios of BCC metals are higher than the fatigue ratios of other metals at room temperature as is also true for metals with nearly the same homologous temperature. The deformation fatigue limit decreases rapidly when Th---0.5 and The-* 1. When T h = 1 then e D = 0, cr D = 0 and ~D/Rm = 0. The deformation fatigue limits of metals belonging to the same subgroup of the periodic element system and having similar homologous temperatures at room temperature are very similar. * Lumumby 10 m. 56, Warsaw 42, Poland. ffs *~ Specific heat content, W r ~ Cp dT + L s is the heat content needed to heat I cm 3 from room 293 temperature to the melting point and to melt the metal at this temperature. * The influence of the structure on the fatigue factor was found by Ferro, Mazetti and Montalenti(3) but they did not consider the influence of the homologous temperature. ** This opinion is contrary to the opinion of another author(6).