On the basis of Tatevskii's additivity rule,we have been able to define 13 different structure elements in hexabasic benzene rings for the estimation of proton chemical shifts by means of a simple but general additivity formula,In this process,the contributions of σ electrons,πelectrons and van der Waals interaction between overcrowded protons in these systems to the proton chemical shifts of planar condensed benzenoid hydrocarbons have been taken into account,The values contributed from these structural eloments to proton chemical shifts are derived from experimental data for 73 protons in 16 planar unsubstituted condensed benzenoid hydrocarbons,These structure elements are certainly more reliable and accurate than those obtained from HMO or SCF quantumchemical calculations for both non-hindered and overcrowded protons.