The EPR analysis of the anion radicals of 1,3,6,8-tetradeuteriopyrene and 1,3,4,5,6,8,9,10-octadeuteriopyrene in THF with K+ at 173 K shows that the observed coupling constant for the protons in the 2,7 positions is decreased in both anion radicals by 25 mG (Delta a(H) = -25 mG) from its value in the anion radical of pyrene itself. This implies that there is only a very small, if any, contribution to this reduction in the spin density at the 2,7 positions resulting from deuterium substitution in the 4,5,9,10 positions. Ab initio calculations (6-31G(**) and 6-311G(**) basis sets) carried out considering the C-D bond to be shorter than the C-H bond by 0.01 Angstrom predict the effects of octadeuteriation to be 21 and 18 mG, respectively, in good agreement with experiment. The calculations do, however, predict an approximately equal contribution from the two tetradeuterio substitution patterns, with the effect of 1,3,6,8-deuteriation being slightly larger than that of 4,5,9,10-tetradeuteriation.