['To evaluate the bispectral index (BIS) and suppression ratio (SR) as very early predictors of neurological outcome during therapeutic hypothermia after cardiac arrest.', 'Demographic data, BIS1, and SR1 were recorded from 97 patients after the first dose of neuromuscular blockade, with outcomes blinded, and compared to the discharge Cerebral Performance Category (CPC). Receiver-operator characteristic curves and a multiple logistic regression model were constructed to predict good (CPC 1-2, GO) and poor (CPC 3-5, PO) neurological outcomes.', 'Fourteen patients were excluded from the final analysis; 33 of the remaining 83 patients (40%) were classified as GO. The BIS1 was higher in patients with GO (37 [28-40] vs. 7 [3-15], p < 0.001). BIS1 < 22 predicted PO with a likelihood ratio (LR) of 14.2 and an area under the curve (AUC) of 0.91 (95% CI 0.85-0.98, p < 0.001). SR1 > or =48 predicted PO with a LR of 12.7 and an AUC of 0.90 (95% CI 0.83-0.98, p < 0.001). Both BIS1 (DeltaAUC 0.16, p = 0.006) and SR1 (DeltaAUC 0.16, p = 0.005) predicted outcomes better than the time to return of spontaneous circulation.'] Are the bispectral index and suppression ratio very early predictors of neurological outcome during therapeutic hypothermia after cardiac arrest?