To investigate the usefulness of pentobarbital (PTB) in the Wada test, 32 patients injected with PTB and 28 patients injected with amobarbital (AMB) were retrospectively analyzed. The AMB and PTB groups did not significantly differ with respect to mean time for recovery to grade III or V motor activity and duration of EEG delta slowing. The incidence of drowsiness or confusion after injection was lower in the PTB group (P=0.043). Language lateralization was well established in both groups. Fifty-three percent of patients in the PTB group and 46.2% in the AMB group with unilateral temporal lobe epilepsy had memory dominance in the nonepileptic hemisphere. The usefulness of PTB in terms of language and memory lateralization was found to be equivalent to that of AMB. Moreover, PTB produced drowsiness and confusion less frequently than AMB, although one patient in the PTB group experienced transient respiratory depression without any sequelae.