Secondary tritium isotope effects have been determined for the elimination reactions of (2-(p-(trifluoromethyl)-phenyl)ethyl-2-t)- and -2-d-2-t)trimethylammonium bromide (1) (EtO-/EtOH), (1-phenylethyl-2-t)- and -2-d(2)-2-t)-trimethylammonium bromide (2) (t-BuO-/t-BuOH), and (1-phenyl-2-(p-chlorophenyl)ethyl-2-t)- and -2-d-2-t)-trimethylammonium bromide (3) (EtO-/EtOH). k(H)(H)/k(H)(T) values at 50 OC were in the range 1.22-1.27 (errors +/- 0.01 or less), with 1 giving the greatest effect. These values are all large enough to suggest significant contributions from tunneling. Studies of the temperature dependences give A(aH)/A(aT) values well below unity (0.60-0.90), and the secondary isotope effect is depressed when deuterium rather than protium is the transferred atom, results which also implicate tunneling. It appears that a carbanion-like E2 transition state is especially conducive to tunneling.