The intracarotid amobarbital or Wada procedure is a component of the presurgical evaluation for refractory epilepsy, during which monitoring the onset and offset of transient anesthetic effects is critical. In this study, we characterized changes of 8 QEEG measures during 26 Wada tests, which included alpha, beta, theta, and delta powers, alpha/delta power ratio (ADR), beta/delta power ratio (BDR), median amplitude-integrated EEG (aEEG) and 90% spectral edge frequency (SEF90), and correlated them with contralateral hemiplegia. We found that on the side of injection, delta and theta powers, ADR, BDR, and SEF90 peaked within 1 min after injection of 70-150 mg amobarbital or 4-7 mg methohexital. When contralateral arm strength returned to 3/5, delta power and aEEG decayed on average 24% and 19%, respectively, for amobarbital, similar to that of methohexital (27% and 18%). Since delta power resolution most closely mirrored that of the hemiplegia and aEEG had the highest signal/noise ratio (SNR), these QEEG values appear to be the best measures for decay of anesthetic effects. Increase in alpha power persisted longest, and therefore may be the best measure of late residual anesthetic effects.