To evaluate the efficacy of combined therapy--hyperbaric oxygenation with nicardipine administration--for neurologic recovery after complete cerebral ischemia. Randomized, prospective, controlled, unblinded, study, with 14-day postischemic observation. Laboratory of the Department of Anesthesiology, Tohoku University School of Medicine. Nineteen healthy mongrel dogs (mean weight 10.4 kg) divided randomly into two groups-ten dogs in the untreated group and nine dogs in the treated group. Fifteen minutes of complete global cerebral ischemia was achieved by occlusion of the ascending aorta and the caval veins. Dogs in the treated group each received a 0.01-mg/kg bolus injection of nicardipine immediately after the reestablishment of circulation, followed by a 0.03-microgram/kg/min continuous infusion of nicardipine for 3 days and hyperbaric oxygen therapy with 3 atmospheres absolute pressures in an FIO2 of 1.0 for 1 hr at 3, 24, and 29 hrs after ischemia. Neurologic recovery was evaluated based on the survival time and rate, the Electroencephalogram (EEG) Score (1 = normal, 5 = isoelectric), and the Neurologic Recovery Score (100 = normal, 0 = brain dead) over a 14-day postischemic period. Neurologic Recovery Scores of the treated group were always higher than those scores of the untreated group throughout the 14-day period. The best Neurologic Recovery Score was 83.1 +/- 5.3 in the treated group and 46.9 +/- 5.2 in the untreated group (p < .01). The numbers of dogs that recovered to a Neurologic Recovery Score of > 85 (assessed as almost normal) was five of nine in the treated group and none of ten in the untreated group (p < .01). Recovery of EEG over 14-day period was better in the treated group. The survival rate and the predicted survival rate were 78% and 13.6 days in the treated group and 30% and 9.0 days in the untreated group, respectively (p < .04 for the survival rate and p < .05 for the survival time). Combined therapy, using hyperbaric oxygenation with nicardipine administration, given after 15 mins of complete global cerebral ischemia, accelerates neurologic recovery in dogs.