Semiââ¬Âempirical values of the natural widths of K, L1, L2, and L3 levels, Kñ1 and Kñ2 xââ¬Âray lines, and KL1L1, KL1L2 and KL2L3 Auger lines for the elements 10?Z?110 are presented in tables and grapahs. Level width Ãâi (i=K, L1,L2, L3) is obtained from the relation Ãâi=ÃâR,i/Ãâ°i, using the theoretical radiative rate ÃâR,i from Scofieldââ¬â¢s relativistic, relaxed Hartreeââ¬ÂFock calculation and the fluorescence yield Ãâ°i from Krauseââ¬â¢s evaluation. Xââ¬Âray and Auger lines widths are calculated as the sums of pertinent level widths. This tabulation of natural level and line widths is internally consistent, and is compatible with all relevant experimental and theoretical information. Present semiââ¬Âempirical widths, especially those of Kñ1 and Kñ2 xââ¬Ârays, are compared with measured widths. Uncertainties of semiââ¬Âempirical values are estimated. © 1981, American Association of Physicists in Medicine. All rights reserved.